365 Days of Astronomy

365 Days of Astronomy http://365daysofastronomy.org An astronomy podcast every day, all year Wed, 16 May 2012 11:00:41 +0000 en hourly 1 http://wordpress.org/?v=3.1 An astronomy podcast every day, all year 365 Days of Astronomy no An astronomy podcast every day, all year 365 Days of Astronomy http://365daysofastronomy.org/wp-content/plugins/powerpress/rss_default.jpg http://365daysofastronomy.org May 16th: GPS http://365daysofastronomy.org/2012/05/16/may-16th-gps/ http://365daysofastronomy.org/2012/05/16/may-16th-gps/#comments Wed, 16 May 2012 11:00:41 +0000 kortney.hogan http://365daysofastronomy.org/?p=7689 Date: May 16, 2012 Title: GPS Podcaster: Steve Nerlich Organization: Cheap Astronomy Links: www.cheapastro.com Description: Cheap Astronomy once again demonstrates that pretty much everything in life has a connection to astronomy. Bio: Cheap Astronomy offers an educational website because in space no-one can hear you podcast. Today's Sponsor: "This episode of 365 days of Astronomy" is sponsored by the Lake County Astronomical Society: Celebrating 30 years of stellar service to members and the public." Additional sponsorship for this episode has also been provided by iTelescope.net - Expanding your horizons in astronomy today. The premier on-demand telescope network, at dark sky sites in Spain, New Mexico and Siding Spring, Australia. Transcript: Hi this is Steve Nerlich from Cheap Astronomy www.cheapastro.com and this is GPS OK – If you don’t have one, you know someone who does, so let’s skip the introductions and get straight down to the astronomy. A standard GPS configuration is a constellation of 24 GPS satellites. The satellites are all at an altitude of 20,200 km with an orbital period of 11 hours and 58 minutes – which means they do exactly 2 orbits for each time the Earth spins once on its axis. Four satellites each follow six orbital planes separated by 60 degrees which surround the Earth in an (airquotes) ‘birdcage’ of criss-crossing orbits. There a link to the relevant Wikipedia article from the Cheap Astronomy podcast page which has a nice animation of a GPS satellite constellation. At last count, there were actually 31 actively transmitting GPS satellites – with these extra number increasing location accuracy and redundancy. There’s been some recent media regarding a growing risk of dropping below the minimum 24 active satellites required to make GPS work effectively, but it remains to be seen if this risk will be realised in the face of the increasing economic importance of maintaining a working GPS system. A GPS satellite broadcasts a signal indicating where it is and the time the signal was broadcast – your receiver then determines, from the time it receives that signal, the distance travelled by the signal, knowing that, being a radio transmission, the signal travels at the speed of light. By making just four calculations from four satellites in the sky, your GPS receiver can then establish its position with respect to latitude, longitude and altitude. It’s all about the conjunction of spheres. Imagine one satellite broadcasting a radio signal. If you pick up that signal and determine it’s a 100 km away, all you really know is that you are somewhere on a surface of a sphere with a 100 km radius that has the satellite at its centre. If there’s two such satellites then you’ll know you are somewhere on the circumference of a circle representing the plane where the two spheres of radio broadcast overlap. Introduce a third satellite and you can narrow down your location to just two points in space which are the points where two differently orientated circle circumferences intersect. Potentially this may be enough to roughly determine your position since you can anticipate you will be on the one of those two points corresponding to the surface of the Earth. But for strictest accuracy – including accuracy in determining your altitude above sea level, the signal from a fourth satellite is required. And that is the idea of the constellation of GPS satellites. Keeping 24 satellites moving in the same orbit, tracing a birdcage of divergent paths around the globe ensures there will always be four satellites in the sky wherever you happen to be on Earth. Now when I say GPS satellites just have to broadcast where they are – actually knowing where they are is a whole separate operation, While the orbital period is predictable, knowing at what point they are on that orbit requires some very accurate time keeping – for which reason each satellite has an atomic clock. Nonetheless, even this isn’t enough, as the orbital paths of the satellites are subject to slight shifting due to the gravitational influence of the Sun and the Moon. To keep track of these changes the satellites are monitored from a fixed, known location on the Earth’s surface – a function currently managed by the 50th Space Wing of the US Airforce Space Command – seriously. Now, given that your GPS receiver is working out its distance from each of four satellites based solely on the time lag of a signal moving at the speed of light from a satellite just over 20,000 kilometres away – there is considerable potential for a margin of error that could see you driving over the embankment into a river when that sexy voice says ‘turn left now’. There are a range of methods to deal with various sources of error. Firstly your GPS receiver carries an electronic almanac of which satellite should be where since confusion can arise when the satellite radio signals get reflected off surroundings, such as tall buildings. This electronic almanac is constructed from calibration data received from the GPS satellites, although these data are generally relayed from a ground-based source – such as Airforce Space Command. The almanac helps your receiver distinguish between garbage signals and genuine GPS signals. The receiver also receives time checks from the satellites since, most GPS receivers determine time from a cheap (not that there’s anything wrong with that) quartz clock rather than the ultra-accurate atomic clocks of the satellites. Clock error is probably the biggest potential source of GPS error, which is why, even though you could almost get away with determining your position from just 3 satellites, it is the fourth reading (which we might call quadrangulation) that ensures the poorer accuracy of the GPS receiver’s clock is effectively accounted for. Interestingly, there’s also relativistic effects to account for, since the satellites move in a weaker gravity field (meaning by general relativity their clocks run faster), and they also move at speed relative to the surface of the Earth (meaning by special relativity their clocks run slower). It turns out that the nett effect is that the satellites’ clocks run about 38 microseconds per day faster than they would at the Earth’s surface. To account for this, the clocks are actually set to run at a slightly lower rate, to keep pace with clocks running on the Earth’s surface. In the world of atomic clocks, various time keeping callibrations are also required to account for changes in the rotation of the Earth – which is influenced by the tidal drag of the Moon , the inertia of the Earth’s molten interior and even the melting of glaciers. Overall, the Earth’s rotation is slowing, leading to a lengthening of a solar day. Consequently a leap second must be introduced to atomic timepieces which measure Universal Coordinated Time (known as UTC – because of the French). In fact, a leap second is required to be added to UTC every 18 months or so because each year (on average) the length of a solar day increases by about 0.002 seconds. The atomic clocks of GPS satellites were aligned to UTC in 1980 – but as of 2009, these atomic clocks in orbit now vary by 19 seconds and to keep it simple we just say they are running at GPS time. Various under-the-hood adjustments are made along the way so that your GPS receiver can tell you the local time wherever you happen to be – as well as telling you where you are of course to within… well, within 10 metres is the general benchmark, although this takes a few minutes to establish after the unit is turned on and the accuracy will degrade with tall trees or buildings around. So, you know, it’s a guide – not an absolute – it’s still a good idea to keep one eye on the road. Thanks for listening. This is Steve Nerlich from Cheap Astronomy, www.cheapastro.com. Cheap Astronomy offers an educational website where you can’t put a price on space. No ads, no profit, just good science. Bye. End of podcast: 365 Days of Astronomy ===================== The 365 Days of Astronomy Podcast is produced by the New Media Working Group of the International Year of Astronomy 2009. Audio post-production by Preston Gibson. Bandwidth donated by libsyn.com and wizzard media. Web design by Clockwork Active Media Systems. You may reproduce and distribute this audio for non-commercial purposes. Please consider supporting the podcast with a few dollars (or Euros!). Visit us on the web at 365DaysOfAstronomy.org or email us at info@365DaysOfAstronomy.org. Until tomorrow...goodbye.]]> http://365daysofastronomy.org/2012/05/16/may-16th-gps/feed/ 0 podcast iya 365 Date: May 16, 2012 - Title: GPS Podcaster: Steve Nerlich - Organization: Cheap Astronomy - Links: www.cheapastro.com - Description: Cheap Astronomy once again demonstrates that pretty much everything in life has a connection to astronomy. - Date: May 16, 2012 Title: GPS Podcaster: Steve Nerlich Organization: Cheap Astronomy Links: www.cheapastro.com Description: Cheap Astronomy once again demonstrates that pretty much everything in life has a connection to astronomy. B... 365 Days of Astronomy no May 15th: Astronomy Word of the Week: Obliquity http://365daysofastronomy.org/2012/05/15/may-15th-astronomy-word-of-the-week-obliquity/ http://365daysofastronomy.org/2012/05/15/may-15th-astronomy-word-of-the-week-obliquity/#comments Tue, 15 May 2012 11:00:14 +0000 kortney.hogan http://365daysofastronomy.org/?p=7687 Date: May 15, 2012 Title: Astronomy Word of the Week: Obliquity Podcaster: Dr. Christopher Crockett Organization: United States Naval Observatory Links: http://christophercrockett.com http://astrowow.wordpress.com/ Description: The tilt of our planet is about much more than the seasons. The astronomy word of the week is "obliquity". Bio: Dr. Christopher Crockett is an astronomer at the United States Naval Observatory in Flagstaff, Arizona. His research involves searching for planets around very young stars (“only” a few million years old). It is hoped that the results from this research will help constrain models of planet formation and lead to a better understanding of where, when, and how often planets form. Chris is also passionate about astronomy outreach and education and will talk for hours about the Universe if you let him. Today's Sponsor: "This episode of 365 days of Astronomy" is sponsored by iTelescope.net - Expanding your horizons in astronomy today. The premier on-demand telescope network, at dark sky sites in Spain, New Mexico and Siding Spring, Australia. This episode has also been sponsored by Lake County Astronomical Society: Celebrating 30 years of stellar service to members and the public. Transcript: The planet you're standing on is not very steady. She bobs and wobbles, ducks and weaves, as she makes her annual trek around the Sun. Our home constantly struggles with forces both external and internal; the Sun, the Moon, and the planets tug her back and forth while shifting masses within force her to constantly find new balance. The tilt of our planet's axis - what astronomers call its obliquity - is one measure of this interplanetary tug-of-war. Obliquity measures how far over a planet or moon is tipped relative to its orbit; in the Earth's case, it's about 23 degrees. We feel the obliquity in the changing seasons. In June, the north pole is tipped towards the Sun. The northern hemisphere experiences longer days and more direct sunlight giving us warm summer days. In December, the north pole is tipped away from the Sun and everyone above the equator experiences the bitter chill of winter as the days get shorter and the sunlight reaches us more obliquely. The other planets in our solar system exhibit a wide range of obliquities. Mars, Saturn, and Neptune are all tipped by roughly the same amount as Earth. Mercury and Jupiter have hardly any obliquity at all - which means no seasons for them. Venus' obliquity is 177 degrees; it is almost completely upside down. Put another way, it rotates in the opposite direction from Earth. Were there ever to be a break in Venus' stifling cloud layer, native Venusians would see the Sun rise in the west and set in the east! Uranus is another strange character; his obliquity is 97 degrees. Uranus is lying on his side! This leads to some very strange days and seasons. Each pole of Uranus alternates between being in constant sunlight for 42 years, then perpetual darkness for another 42 years. Only a very thin strip along the equator experiences anything like day/night cycles that we experience - and even then the Sun is frequently sitting very low on the horizon. Astronomers aren't entirely certain how Venus and Uranus came to have such extreme obliquities. A leading hypothesis is that both experienced massive collisions at some point in their distant past, essentially knocking them over. A glancing blow from a minor planet isn't the only thing that can change an obliquity. The tilt of our planet's axis is drifting - ever so slightly - all the time. The poles actually trace out a rather complex dance over time scales ranging from minutes to thousands of centuries. Like a spinning top, our planet also wobbles - though it does so very slowly. Over a period of 26,000 years, the poles trace out a giant circle in the sky. Right now, the north pole points pretty close to the star Polaris. But over time that will change, and in some epochs it will be pointing at nothing at all. This wobble - or precession - doesn't change the amount of obliquity; it simply changes where in space the poles are pointing. The Moon, however, does tug on our planet's axis. In addition to rotation and precession, the Earth experiences something called nutation. This is a slight rocking of the Earth's axis caused by the changing positions of the Moon, the Sun, and all the other bodies in the solar system. With many players involved, the motion from nutation is fairly complex. The main component nods the planet by a couple hundred meters over a nearly 19 year cycle that is tied to how the Moon's orbit drifts around the Earth. Our planet also has to contend with forces much closer to home. Internal motions of magma, deep sea currents, changing ocean salinity, winds, melting ice sheets, and even earthquakes all conspire to constantly change the distribution of mass within the Earth. The planet responds by continuously shifting its spin axis - an effect known as polar motion. This is a bit different than nutation; it actually changes where on Earth the north and south poles are located. Hard as it may be to fathom, these are not fixed locations on the globe. The drift is very small - centimeters per year - but it does add a complex twist to understanding our planets motion in space. The presence of a large moon is believed to help stabilize our obliquity. The tilt does change by a few degrees over many millions of years, but manages to hold steady at around 20-25 degrees. Mars, conversely, appears to be going through a chaotic evolution in its obliquity. Computer simulations of its stability suggest that, over the past few million years, the Red Planet's tilt has oscillated wildly between zero and sixty degrees which may lead to drastic swings in the environment. Many astrobiologists - scientists who study the evolution and origin of life in a cosmic context - argue that our moon may be an essential ingredient for providing a stable environment within which life could thrive. Does this mean that the existence of complex life and advanced civilizations is dependent on the presence of a large satellite? That's hard to say. It is certainly plausible that our closest neighbor in space has been an indispensable partner in the evolution of our species. I'm continually amazed at how a simple concept - like the tilt of a planet - can actually lead down a labyrinthian path of subtleties. Studying Earth's obliquity, and the obliquity of all the other planets and moons, reveals much about the dynamics of our planet, the interplay of our home and neighboring worlds, and even the often times cataclysmic evolution of the solar system. While the subtleties are far removed from our day-to-day lives, our Earth's position in space actually is inseparable from the human experience. The June solstice is just over a month away. Whether you're bundling up for winter, or heading to the beach for summer, remember: the Earth's obliquity is the reason for the seasons! End of podcast: 365 Days of Astronomy ===================== The 365 Days of Astronomy Podcast is produced by the New Media Working Group of the International Year of Astronomy 2009. Audio post-production by Preston Gibson. Bandwidth donated by libsyn.com and wizzard media. Web design by Clockwork Active Media Systems. You may reproduce and distribute this audio for non-commercial purposes. Please consider supporting the podcast with a few dollars (or Euros!). Visit us on the web at 365DaysOfAstronomy.org or email us at info@365DaysOfAstronomy.org. Until tomorrow...goodbye.]]> http://365daysofastronomy.org/2012/05/15/may-15th-astronomy-word-of-the-week-obliquity/feed/ 0 podcast iya 365 Date: May 15, 2012 - Title: Astronomy Word of the Week: Obliquity Podcaster: Dr. Christopher Crockett - Organization: United States Naval Observatory - Links: http://christophercrockett.com http://astrowow.wordpress.com/ - Date: May 15, 2012 Title: Astronomy Word of the Week: Obliquity Podcaster: Dr. Christopher Crockett Organization: United States Naval Observatory Links: http://christophercrockett.com http://astrowow.wordpress.com/ Description: The tilt of our planet is about much more than the seasons. The astronomy word of the week is "obliquity". Bio: Dr. Christopher Crockett is an astronomer at the United States Naval Observatory in Flagstaff, Arizona. His research involves searching for planets around very young stars (“only” a few million years old). It is hoped that the results from this research will help constrain models of planet formation and lead to a better understanding of where, when, and how often planets form. Chris is also passionate about astronomy outreach and education and will talk for hours about the Universe if you let him. Today's Sponsor: "This episode of 365 days of Astronomy" is sponsored by iTelescope.net - Expanding your horizons in astronomy today. The premier on-demand telescope network, at dark sky sites in Spain, New Mexico and Siding Spring, Australia. This episode has also been sponsored by Lake County Astronomical Society: Celebrating 30 years of stellar service to members and the public. Transcript: The planet you're standing on is not very steady. She bobs and wobbles, ducks and weaves, as she makes her annual trek around the Sun. Our home constantly struggles with forces both external and internal; the Sun, the Moon, and the planets tug her back and forth while shifting masses within force her to constantly find new balance. The tilt of our planet's axis - what astronomers call its obliquity - is one measure of this interplanetary tug-of-war. Obliquity measures how far over a planet or moon is tipped relative to its orbit; in the Earth's case, it's about 23 degrees. We feel the obliquity in the changing seasons. In June, the north pole is tipped towards the Sun. The northern hemisphere experiences longer days and more direct sunlight giving us warm summer days. In December, the north pole is tipped away from the Sun and everyone above the equator experiences the bitter chill of winter as the days get shorter and the sunlight reaches us more obliquely. The other planets in our solar system exhibit a wide range of obliquities. Mars, Saturn, and Neptune are all tipped by roughly the same amount as Earth. Mercury and Jupiter have hardly any obliquity at all - which means no seasons for them. Venus' obliquity is 177 degrees; it is almost completely upside down. Put another way, it rotates in the opposite direction from Earth. Were there ever to be a break in Venus' stifling cloud layer, native Venusians would see the Sun rise in the west and set in the east! Uranus is another strange character; his obliquity is 97 degrees. Uranus is lying on his side! This leads to some very strange days and seasons. Each pole of Uranus alternates between being in constant sunlight for 42 years, then perpetual darkness for another 42 years. Only a very thin strip along the equator experiences anything like day/night cycles that we experience - and even then the Sun is frequently sitting very low on the horizon. Astronomers aren't entirely certain how Venus and Uranus came to have such extreme obliquities. A leading hypothesis is that both experienced massive collisions at some point in their distant past, essentially knocking them over. A glancing blow from a minor planet isn't the only thing that can change an obliquity. The tilt of our planet's axis is drifting - ever so slightly - all the time. The poles actually trace out a rather complex dance over time scales ranging from minutes to thousands of centuries. Like a spinning top, our planet also wobbles - though it does so very slowly. Over a period of 26,000 years, the poles trace out a giant circle in the sky. Right now, the north pole points pretty close to the star Polaris. 365 Days of Astronomy no May 14th: Diamond Planet Finder Is A Star http://365daysofastronomy.org/2012/05/14/may-14th-diamond-planet-finder-is-a-star/ http://365daysofastronomy.org/2012/05/14/may-14th-diamond-planet-finder-is-a-star/#comments Mon, 14 May 2012 11:00:46 +0000 kortney.hogan http://365daysofastronomy.org/?p=7683 Date: May 14, 2012 Title: Diamond Planet Finder Is A Star Podcaster: Michael Greenwell Links: http://michaelgreenwell.wordpress.com/ and http://exitstageright.wordpress.com/ Description: Last year, after making an enormously publicized discovery astronomer Matthew Bailes used his moment of fame to defend his scientific colleagues and to try to point us in the direction in which we need to be looking. I think he should be applauded for this and we would do well to listen to what he had to say. Bio: Michael Greenwell has worked, at various times, as a university tutor, a barman, a DJ (not a very good one), an office lackey, supermarket worker, president of a small charity, a researcher, a librarian, a volunteer worker in Nepal during the civil war there, and some other things that were too tedious to mention. He blogs here and also runs the animal extinction site Exit Stage Right. Today's Sponsor: "This episode of 365 days of Astronomy is sponsored by 'The Heliochromologist' " "This episode of 365 days of astronomy was sponsored by iTelescope.net - Expanding your horizons in astronomy today. The premier on-demand telescope network, at dark sky sites in Spain, New Mexico and Siding Spring, Australia." Transcript: At the end of last August, you probably read about the scientists who found a planet that is, in their words “certainly crystalline” or in other words, a large…. well… ok…a VERY large diamond…in fact, it is about 4 times the diameter of the Earth. The planet orbits a pulsar, which they referred to as Beyonce on account of the amount of Bling it was showing off. The story got a lot of coverage but one of the scientists involved, Matthew Bailes, did something a couple of weeks later that was rather brave and just as worthy of note - and I think that he should be applauded for it and that we would do well to listen to what he had to say. Specifically, he wrote an article for an Australian website called “The Conversation” in which he used the opportunity the extensive media coverage this discovery gave him to defend climate scientists and try to draw people’s attention to a problem that is ever worsening ie the fact that while the media are happy to report about weird weather on Jupiter or Saturn for example, they show a certain reluctance to talk about Global Weirding and the problems of Climate change here on planet Earth. I’ll quote to you now a slightly shortened version of what he said…

Following the publication of our finding in the journal Science, our research received amazing attention from the world’s media. I was asked by many journalists about the significance of the discovery. If I were honest, I’d have to concede that, although worthy of publication in Science, in the field of astrophysics it isn’t that significant. And yet the diamond planet has been hugely successful in igniting public curiosity about the universe in which we live. Imagine for a minute that, instead of discovering a diamond planet, we’d made a breakthrough in global temperature projections. Let’s say we studied computer models of the influence of excessive greenhouse gases, verified them through observations, then had them peer-reviewed and published in Science. Instead of sitting back and basking in the glory, I suspect we’d find a lot of commentators, many with no scientific qualifications, pouring scorn on our findings. People on the fringe of science would be quoted as opponents of our work, arguing that it was nothing more than a theory yet to be conclusively proven. Before long our credibility and findings would be under serious question. But luckily we’re not climate scientists. It may come as a big surprise to many, but there is actually no difference between how science works in astronomy and climate change – or any other scientific discipline for that matter. We make observations, run simulations, test and propose hypotheses, and undergo peer review of our findings. Of course we all make mistakes. But eventually the prevailing wisdom of the community triumphs and the field advances. It’s wonderful to be a part of that process. But on occasion those from the fringe of the scientific community will push a position that is simply not credible against the weight of evidence. This occurs within any discipline. But it seems it’s only in the field of climate science that such people are given airtime and column inches to espouse their views. Those who want to ignore what’s happening to Earth feel they need to be able to quote “alternative studies”, regardless of the scientific merit of those studies. In all fields of science, papers are challenged and statistics are debated. If there is any basis to these challenges they stand, but if not they fall by the wayside and the field continues to advance. When big theories fall, it isn’t because of business or political pressures – it’s because of the scientific process. Sadly, the same media commentators who celebrate diamond planets without question are all too quick to dismiss the latest peer-reviewed evidence that suggests man-made activities are responsible for changes in concentrations of CO2 in our atmosphere. The scientific method is universal. If we selectively ignore it in certain disciplines, we do so at our peril.

OK, So there you have it. This guy took what he described himself as his 15 minutes of fame, and used it to say something that was in dire need of saying and at the cost of making himself suspect for some of the media. The personal sacrifice of downplaying his own discovery in order to support the climate scientists that are constantly under attack and to support the environment is not to something be sniffed at. However, an article such as the one he wrote in afterwards receives hardly any coverage compared to the discovery of the planet, and such an article is usually smothered in an atmosphere that is so thick full of obfuscating and false reports about climate change, it’s almost worthy of Venus. These reports are being produced for many of the world’s great energy companies and they are being done by many of the PR groups that were initially employed by tobacco companies in order to try and convince people that smoking wasn’t bad for them. Eventually they lost that battle and with a bit of work we can ensure that they lose this one before our atmosphere ends up like Venus too. That’s why for me, the Diamond Planet Finder is a star and we should appreciate what he did, and act on what he said. From somewhere in the currently breathable and livable atmosphere of Planet Earth, this is Michael Greenwell Michaelgreenwell.wordpress.com End of podcast: 365 Days of Astronomy ===================== The 365 Days of Astronomy Podcast is produced by the New Media Working Group of the International Year of Astronomy 2009. Audio post-production by Preston Gibson. Bandwidth donated by libsyn.com and wizzard media. Web design by Clockwork Active Media Systems. You may reproduce and distribute this audio for non-commercial purposes. Please consider supporting the podcast with a few dollars (or Euros!). Visit us on the web at 365DaysOfAstronomy.org or email us at info@365DaysOfAstronomy.org. Until tomorrow...goodbye.]]> http://365daysofastronomy.org/2012/05/14/may-14th-diamond-planet-finder-is-a-star/feed/ 0 podcast iya 365 Date: May 14, 2012 - Title: Diamond Planet Finder Is A Star Podcaster: Michael Greenwell - Links: http://michaelgreenwell.wordpress.com/ and http://exitstageright.wordpress.com/ - Description: Last year, Date: May 14, 2012 Title: Diamond Planet Finder Is A Star Podcaster: Michael Greenwell Links: http://michaelgreenwell.wordpress.com/ and http://exitstageright.wordpress.com/ Description: Last year, after making an enormously publicized discovery astronomer Matthew Bailes used his moment of fame to defend his scientific colleagues and to try to point us in the direction in which we need to be looking. I think he should be applauded for this and we would do well to listen to what he had to say. Bio: Michael Greenwell has worked, at various times, as a university tutor, a barman, a DJ (not a very good one), an office lackey, supermarket worker, president of a small charity, a researcher, a librarian, a volunteer worker in Nepal during the civil war there, and some other things that were too tedious to mention. He blogs here and also runs the animal extinction site Exit Stage Right. Today's Sponsor: "This episode of 365 days of Astronomy is sponsored by 'The Heliochromologist' " "This episode of 365 days of astronomy was sponsored by iTelescope.net - Expanding your horizons in astronomy today. The premier on-demand telescope network, at dark sky sites in Spain, New Mexico and Siding Spring, Australia." Transcript: At the end of last August, you probably read about the scientists who found a planet that is, in their words “certainly crystalline” or in other words, a large…. well… ok…a VERY large diamond…in fact, it is about 4 times the diameter of the Earth. The planet orbits a pulsar, which they referred to as Beyonce on account of the amount of Bling it was showing off. The story got a lot of coverage but one of the scientists involved, Matthew Bailes, did something a couple of weeks later that was rather brave and just as worthy of note - and I think that he should be applauded for it and that we would do well to listen to what he had to say. Specifically, he wrote an article for an Australian website called “The Conversation” in which he used the opportunity the extensive media coverage this discovery gave him to defend climate scientists and try to draw people’s attention to a problem that is ever worsening ie the fact that while the media are happy to report about weird weather on Jupiter or Saturn for example, they show a certain reluctance to talk about Global Weirding and the problems of Climate change here on planet Earth. I’ll quote to you now a slightly shortened version of what he said… Following the publication of our finding in the journal Science, our research received amazing attention from the world’s media. I was asked by many journalists about the significance of the discovery. If I were honest, I’d have to concede that, although worthy of publication in Science, in the field of astrophysics it isn’t that significant. And yet the diamond planet has been hugely successful in igniting public curiosity about the universe in which we live. Imagine for a minute that, instead of discovering a diamond planet, we’d made a breakthrough in global temperature projections. Let’s say we studied computer models of the influence of excessive greenhouse gases, verified them through observations, then had them peer-reviewed and published in Science. Instead of sitting back and basking in the glory, I suspect we’d find a lot of commentators, many with no scientific qualifications, pouring scorn on our findings. People on the fringe of science would be quoted as opponents of our work, arguing that it was nothing more than a theory yet to be conclusively proven. Before long our credibility and findings would be under serious question. But luckily we’re not climate scientists. It may come as a big surprise to many, but there is actually no difference between how science works in astronomy and climate change – or any other scientific discipline for that matter. We make observations, run simulations, test and propose hypotheses, 365 Days of Astronomy no May 13th: Encore: Exploring Space from Space http://365daysofastronomy.org/2012/05/13/may-13th-encore-exploring-space-from-space/ http://365daysofastronomy.org/2012/05/13/may-13th-encore-exploring-space-from-space/#comments Sun, 13 May 2012 15:04:40 +0000 kortney.hogan http://365daysofastronomy.org/?p=7681 Date: May 13, 2012 Title: Encore: Exploring Space from Space Podcaster: Kenneth Renshaw Links: Solar System Ambassador Website: http://www2.jpl.nasa.gov/ambassador/profiles/Kenneth_Renshaw.htm Saturn Observation Campaign Website: http://soc.jpl.nasa.gov/members-state.cfm?state=AR This podcast originally aired on April 12th, 2009 http://365daysofastronomy.org/2009/04/12/april-12th-exploring-space-from-space/ Description: Kenneth Renshaw is a college music instructor, piano teacher/tuner/technician, church choir director/pianist, photographer and videographer from the small town of Piggott, Arkansas. He graduated from Southern Baptist College and Arkansas State University with Associate, Bachelor, and Masters degrees in music education, but has had the hobby of amateur astronomy since before the age of 16. He is a Solar System Ambassador and a member of the Saturn Observation Campaign for NASA’s Jet Propulsion Laboratory and does space presentations for numerous schools and organizations. He is married to Rachel Burden, with 2 stepdaughters, Melody, 16, and Liberty, 15. Bio: Almost since the beginning of the space age, NASA and the other space programs have used spacecraft to actively research astronomy, from our solar system to the furthest reaches of the universe. This podcast is a brief summary of the current spacecraft being used to explore astronomy-from the nearby Moon to the edge of the observable universe, the Cosmic Background Radiation. Today's Sponsor: This episode of 365 days of astronomy was sponsored by iTelescope.net - Expanding your horizons in astronomy today. The premier on-demand telescope network, at dark sky sites in Spain, New Mexico and Siding Spring, Australia. Transcript: Welcome to the podcast: Exploring Space from Space. I’m Kenneth Renshaw, a member of the Saturn Observation Campaign and a Solar System Ambassador for NASA. Almost since the beginning of the space age, NASA and the other space programs have used spacecraft to actively research astronomy, from our solar system to the furthest reaches of the universe. This podcast is a brief summary of the current spacecraft being used to explore astronomy-from the nearby Moon to the edge of the observable universe, the Cosmic Background Radiation. To stay within reasonable time limits, we will focus on spacecraft used for astronomy, rather than the hundreds of satellites used to study the earth. First, the nearest star, our Sun. For obvious reasons (the heat), satellites that study the Sun are usually in a distant orbit around it, such as at the Earth’s distance. There are many probes studying the Sun and its effect on the Earth. Ulysses is a spacecraft that orbits the Sun in a polar orbit, giving us the first look at the polar regions of the Sun. SOHO, the Solar and Heliospheric Observatory, is a joint effort of NASA and the European Space Agency, launched in December 1995 to an area beyond Earth’s orbit. It has 3 instruments that can monitor the interior of the Sun in a science called helioseismology. The FAST, a low altitude mission around the Earth, and POLAR, at a high altitude, are used together to study the particles, charge, and magnetism in the ionosphere and how they affect the Oxygen in Earth’s atmosphere. Launched in 1997, ACE studies the solar wind from a Lagrange point between the Earth and the Sun. In 2000, the European Space Agency launched CLUSTER, a set of 4 spacecraft in Earth orbit, studying the interaction of the solar wind and the magnetosphere, particularly the magnetic reconnection events that cause solar storms. The 2000 launch of IMAGE began the imaging of the plasmas above the Earth, with far and extreme ultraviolet, neutral atom imaging, and radio sounding. It is in a highly elliptical orbit around the Earth. TWINS, or Two Wide-angle Imaging Neutral-atom Spectrometers, are 2 spacecraft in a high orbit of the Earth, giving a 3-D view of the magnetosphere. THEMIS, a 2 year mission using 5 identical orbiters, is studying the auroras in improving our predictions of Space Weather., Solar-B or Hinode is a Japanese, United Kingdom, and NASA collaboration in a sun-synchronous polar orbit, launched in 2006. It studies the sun in high resolution visual, ultraviolet, and X-Ray wavelengths. The 2006 mission, STEREO, or Solar Terrestrial Relations Observatory, consists of 2 spacecraft positioned one ahead and one behind Earth’s orbit, providing a stereoscopic view of solar activity, enabling more accurate predictions of when that activity will affect Earth, as well as one of the probes showing us the activity on the hidden side of the Sun before it rotates around to our side, also enabling better forecasting. The Advanced Composition Explorer, or ACE, is at a Lagrange Point between the Earth and Sun, studying solar, as well as interstellar particles. Earlier this year, the IBEX, or Interstellar Boundary Explorer, was launched in a high orbit 2/3 of the way to the Moon. It collects particles from the boundary of the Sun’s influence, far beyond Pluto. It will study what is known as the Termination Shock, where interstellar wind begins to mix with the Solar wind. Planetary probes are spacecraft that actually visit these worlds, sometimes landing on them. Starting at the first planet, Mercury, the first spacecraft designed to orbit the planet is on its was to the hot, airless world near the Sun after a 2004 launch. Messenger—the Mercury Surface, Space Environment, Geochemistry, and Ranging Mission—has made 2 flybys of Mercury so far, and, after another flyby in September of this year, will go into orbit on March 18, 2011. It will make a comprehensive study of Mercury for 1 year. At the cloud-enshrouded, and therefore, hottest planet, with a runaway greenhouse effect, the Venus Express was placed into orbit around the second planet in April 2006 by ESA, the European Space Agency. Among its many instruments is the ability to monitor Venus from the thermal infrared to the ultraviolet wavelengths. At the Moon, the SELENE (also known as Kaguya) is in orbit, sent by JAXA, the Japanese Space Agency, as is Chandrayaan 1, a project of India. To be launched in early June is NASA’s Lunar Reconnaissance Orbiter along with an impactor, LCROSS. Colliding into a permanently shaded crater at one of the Moon’s poles, the LCROSS should kick up a plume of vapor from the theorized water ice in the crater, giving astronauts a source of water and fuel for a future lunar base. At Mars are 3 spacecraft on the surface--a lander that recently completed its mission at the north polar region, Phoenix, and the rovers, Spirit and Opportunity. The 2 rovers were planned for a 90 day mission in 2004, but have been extremely successful over the past 5 years—20 times the expected time, a surprise for everyone. Next roving on the surface will be the Mars Science Laboratory, to be launched in 2011. In orbit around Mars is NASA’s Mars Odyssey and the high-resolution cameras of the Mars Reconnaissance Orbiter, as well as Europe’s Mars Express. On its way to orbit not one, but 2 objects in the asteroid belt, is Dawn. It will orbit the asteroid Vesta, and the former asteroid promoted to a dwarf planet, Ceres. It will then be the first spacecraft in history to orbit 2 objects. No spacecraft is currently around Jupiter, after the conclusion of the Galileo mission, that plunged through the crushing atmosphere of Jupiter in September 2003. However, the New Horizons recently flew by and studied Jupiter, as well as steal a microscopic bit of Jupiter’s orbital momentum to give it a boost to its destination of Pluto. At Saturn is the highly successful orbiter, Cassini, now in a two-year extension of an original 4-year mission. It has studied Saturn, its rings, its magnetospheric environment, and its moons. In January 2005, an attached lander, Huygens, landed on the haze enshrouded moon, Titan. Titan is the only moon in the Solar System that has a thick atmosphere, and is a cold version of the biochemistry of early Earth. No probes since Voyager 2 have visited Uranus or Neptune. On its way to Pluto is the New Horizons. Coincidentally, on my 20th wedding anniversary on July 14, 2015, New Horizons will fly by Pluto and its 3 moons, and then go on to fly by a yet determined destination in the Kuiper belt. When Deep Impact hit Comet Tempel 1 on the 4th of July of 2005, it left a crater that, unfortunately, was too enshrouded in a dust plume to be observed. The Stardust spacecraft, that collected comet particles from Wild 2, is now on it way to Tempel 1 to check the remains of this collision. Meanwhile, Deep Impact is now called Epoxi, and is now studying extrasolar planets that transit their stars, and will also fly by Comet Hartley next year. This is getting 2 for the price of one, using these 2 spacecraft. We have now toured the main objects of the Solar System. Let now go back to Earth, where a number of spacecraft are orbiting, and studying things far beyond the Sun’s domain, even to the very edge of the observable universe. Telescopes and other instruments are placed in orbit, since our atmosphere blurs and can actually block much of the electromagnetic radiation we need to study to get a complete picture of the universe. In visible light and the near ultraviolet and infrared we have the Hubble Space Telescope; in the infrared, we have the Spitzer Space Telescope. SOFIA is an infrared telescope onboard an aircraft. GALEX, or Galaxy Evolution Explorer, is an ultraviolet probe, photographing millions of galaxies in the UV since 2003. To pick up the X-Ray, we have Chandra, the Japanese/US collaboration, Suzaku, and Europe’s XMM-Newton. RXTE, the Rossi X-Ray Timing Explorer studies black holes, neutron stars, X-Ray Pulsars, and X-Ray bursts in this frequency. CHIPS, or the Cosmic Hot Interstellar Plasma Spectrometer is monitoring the plasma in our galaxy. Last month, Kepler was launched to constantly monitor the light output of 100,000 stars and detect any planets passing in front of their star, and try to find out what percentage of stars have planets in the habitable zone. The Fermi spacecraft (formerly called GLAST for Gamma Ray Large Area Space Telescope) monitors the sky for Gamma Ray Bursts, and also has a telescope to study this high-energy radiation. On the other hand, the Swift spacecraft studies bursts in Gamma Rays, X Rays, UV, and Optical wavelengths. HETE-2 has, for over 6 years, also been used to detect these most massive explosions in the universe. Integral is a gamma ray spectrometer launched by the European Space Agency. And lastly, WMAP, the Wilkinson Microwave Anisotropy Probe, has, in high resolution, mapped the Cosmic Background Radiation and determined the universe to be 13.73 billion years old, +/- 1%. Thanks for joining us for a more clear view of the universe, thanks to the space age, and thanks for listening to 365 Days of Astronomy. End of podcast: 365 Days of Astronomy ===================== The 365 Days of Astronomy Podcast is produced by the New Media Working Group of the International Year of Astronomy 2009. Audio post-production by Preston Gibson. Bandwidth donated by libsyn.com and wizzard media. Web design by Clockwork Active Media Systems. You may reproduce and distribute this audio for non-commercial purposes. Please consider supporting the podcast with a few dollars (or Euros!). Visit us on the web at 365DaysOfAstronomy.org or email us at info@365DaysOfAstronomy.org. Until tomorrow...goodbye.]]> http://365daysofastronomy.org/2012/05/13/may-13th-encore-exploring-space-from-space/feed/ 0 podcast iya 365 Date: May 13, 2012 - Title: Encore: Exploring Space from Space - Podcaster: Kenneth Renshaw - Links: Solar System Ambassador Website: http://www2.jpl.nasa.gov/ambassador/profiles/Kenneth_Renshaw.htm Saturn Observation Campaign Website: Date: May 13, 2012 Title: Encore: Exploring Space from Space Podcaster: Kenneth Renshaw Links: Solar System Ambassador Website: http://www2.jpl.nasa.gov/ambassador/profiles/Kenneth_Renshaw.htm Saturn Observation Campaign Website: http://soc.jpl.nasa.gov/members-state.cfm?state=AR This podcast originally aired on April 12th, 2009 http://365daysofastronomy.org/2009/04/12/april-12th-exploring-space-from-space/ Description: Kenneth Renshaw is a college music instructor, piano teacher/tuner/technician, church choir director/pianist, photographer and videographer from the small town of Piggott, Arkansas. He graduated from Southern Baptist College and Arkansas State University with Associate, Bachelor, and Masters degrees in music education, but has had the hobby of amateur astronomy since before the age of 16. He is a Solar System Ambassador and a member of the Saturn Observation Campaign for NASA’s Jet Propulsion Laboratory and does space presentations for numerous schools and organizations. He is married to Rachel Burden, with 2 stepdaughters, Melody, 16, and Liberty, 15. Bio: Almost since the beginning of the space age, NASA and the other space programs have used spacecraft to actively research astronomy, from our solar system to the furthest reaches of the universe. This podcast is a brief summary of the current spacecraft being used to explore astronomy-from the nearby Moon to the edge of the observable universe, the Cosmic Background Radiation. Today's Sponsor: This episode of 365 days of astronomy was sponsored by iTelescope.net - Expanding your horizons in astronomy today. The premier on-demand telescope network, at dark sky sites in Spain, New Mexico and Siding Spring, Australia. Transcript: Welcome to the podcast: Exploring Space from Space. I’m Kenneth Renshaw, a member of the Saturn Observation Campaign and a Solar System Ambassador for NASA. Almost since the beginning of the space age, NASA and the other space programs have used spacecraft to actively research astronomy, from our solar system to the furthest reaches of the universe. This podcast is a brief summary of the current spacecraft being used to explore astronomy-from the nearby Moon to the edge of the observable universe, the Cosmic Background Radiation. To stay within reasonable time limits, we will focus on spacecraft used for astronomy, rather than the hundreds of satellites used to study the earth. First, the nearest star, our Sun. For obvious reasons (the heat), satellites that study the Sun are usually in a distant orbit around it, such as at the Earth’s distance. There are many probes studying the Sun and its effect on the Earth. Ulysses is a spacecraft that orbits the Sun in a polar orbit, giving us the first look at the polar regions of the Sun. SOHO, the Solar and Heliospheric Observatory, is a joint effort of NASA and the European Space Agency, launched in December 1995 to an area beyond Earth’s orbit. It has 3 instruments that can monitor the interior of the Sun in a science called helioseismology. The FAST, a low altitude mission around the Earth, and POLAR, at a high altitude, are used together to study the particles, charge, and magnetism in the ionosphere and how they affect the Oxygen in Earth’s atmosphere. Launched in 1997, ACE studies the solar wind from a Lagrange point between the Earth and the Sun. In 2000, the European Space Agency launched CLUSTER, a set of 4 spacecraft in Earth orbit, studying the interaction of the solar wind and the magnetosphere, particularly the magnetic reconnection events that cause solar storms. The 2000 launch of IMAGE began the imaging of the plasmas above the Earth, with far and extreme ultraviolet, neutral atom imaging, and radio sounding. It is in a highly elliptical orbit around the Earth. TWINS, or Two Wide-angle Imaging Neutral-atom Spectrometers, are 2 spacecraft in a high orbit of the Earth, giving a 3-D view of the magnetosphere. 365 Days of Astronomy no May 12th: Encore: Our Place in Space http://365daysofastronomy.org/2012/05/12/may-12th-encore-our-place-in-space/ http://365daysofastronomy.org/2012/05/12/may-12th-encore-our-place-in-space/#comments Sat, 12 May 2012 11:00:59 +0000 kortney.hogan http://365daysofastronomy.org/?p=7675 Date: May 12, 2012 Title: Encore: Our Place in Space Podcaster: Pamela Gay Organization: Astronomy Cast, Star Stryder This podcast originally aired on May 18th, 2010 http://365daysofastronomy.org/2010/05/18/may-18th-our-place-in-space/ Description: From the surface of the Earth, it is easy to feel safe, and in control because we have the knowledge to understand the universe. But we are small, and life is fragile in this vast universe, and there are more things in heaven and earth waiting to be discovered than are dreamt of in all our sciences. In this podcast I try and provide context on both out place in time and in space, and just how fragile our human existence really is. Bio: Dr. Pamela Gay is a professor at Southern Illinois University-Edwardsville. She is also an astronomer, writer, and podcaster focused on using new media to engage people in science and technology. Listen to her weekly on one of the most popular astronomy podcasts, Astronomy Cast. Follow her on her blog, Star Stryder. Sponsor:This episode of 365 days of astronomy was sponsored by iTelescope.net - Expanding your horizons in astronomy today. The premier on-demand telescope network, at dark sky sites in Spain, New Mexico and Siding Spring, Australia. Transcript: Welcome to 365 Days of Astronomy. This is Pamela Gay of Astronomy Cast and StarStryder.com coming to you from Southern Illinois. On this Rainy spring day it seems like all the world is in my backyard, and most of it is triggering hay fever. The truth is, h ere on the surface of the Earth it is easy to see our universe as small and understood. Each year the seasons tick past in explainable ways, and 400 years after Kepler, the motion of the planets is just something we take for granted. Solar eclipses no longer make people tremble as the Asseryians trembled on the battlefield during the 763BC, instead the tremble in anticipation of the perfect picture during the astronomical eclipse tours. Today eclipses are just a roughly twice a year things that thousands of people turn into vacations. From the surface of the Earth, it is easy to feel safe, and in control because we have the knowledge to understand the universe. We have science to explain the supernovae, the comets, the every twinkle and gleam in the sky. But we are small, and life is fragile in this vast universe, and there are more things in heaven and earth waiting to be discovered than are dreamt of in all our sciences. Our human minds struggles to grasp at the scale of our universe. Any number over a million is simply large, and in discussing the cosmos, we discuss the billions and billions of galaxies, the billions and billions of stars, and distances so vaste that light has not yet had time to travel from most distant galaxies we see in the north to the most distant galaxies we see in our Southern skies. In this universe defined by unimaginable billions, it is easy to lose track of our place in the context of space. Carl Sagan referred to the earth as a Pale Blue Dot and in images taken by the Cassini space probe as orbited Saturn, we can see the distant Earth in its smallness. Sagan wrote of our world, “Look again at that dot. That’s here, that’s home, that’s us. On it everyone you love, everyone you know, everyone you ever heard of, every human being who ever was, lived out their lives. The aggregate of our joy and suffering, thousands of confident religions, ideologies, and economic doctrines, … every king and peasant, every young couple in love, every mother and father, hopeful child, inventor and explorer, every teacher of morals, every corrupt politician, every ’superstar,’ every ’supreme leader,’ every saint and sinner in the history of our species lived there – on a mote of dust suspended in a sunbeam.” Sagan worked to express our smallness, but this isn’t our only struggle. We also struggle to understand our place in the vastness of time. Our planet is a transitory thing. Formed roughly 4.5 billion years ago, it will be able to support life for only another 50 million years before the Sun’s slow increase in temperature makes life intolerable on Earth. In roughly 5 billion years our Earth will be destroyed entirely as our Sun bloats into a red giant and either consumes the planet or simply broils it with intense solar winds. We live in the twilight years of our world, and time is ticking. But our planet is just part of a cycle. We live on a rocky world orbiting a star that is rich in heavy elements. If you shine sunlight through the most amazing of prisms to make a rainbow, you will be able to single out dark stripes mixed in the light, many of which arise from Iron, Titanium, and other metallic atoms in the sun’s atmosphere. To get at this richness of atomic diversity, our universe had to be created, and generations of stars had to live and die, all before our own Sun could be born. When our universe formed, 13.7 billion years ago, it was pure energy – pure light. Within the first fractions of a second, that energy began to solidify into particles. Mass and Energy are just two faces of the same thing, and as the universe cooled, the mass divided from the light. At first there was matter and anti-matter, but through the miracle of asymmetry, for every 1 billion anti-matter particles there was a billion and 1 matter particles. The particles collided – they destroyed one another, and they left behind matter. And that matter, at that moment, and for almost the next 3 minutes, was as hot and as dense as the center of a star and nuclear fusion was able to take place. Protons combined. Neutrons were created. Hydrogen nuclei grew into deuterium, which in turn fused to helium and trace amounts of lithium and beryllium. Our theories tell us the ratios of these reactions, and when we look out at the oldest stars, we find the correct fractions fossilized in the elemental abundances of these ancient stars’ light. This is just one of many lines of evidence proving the big bang. After the first 3 minutes, nuclear reactions shut off, but the universe was still too hot for neutral atoms to form. Everything was an opaque mash of nuclei and electrons and light, colliding. It stayed too hot, and it stayed opaque for nearly 300,000 years, but then one day it cooled enough that the electrons could bond with the atomic nuclei, and when that happened the light was released. Today we see this escaping light as the cosmic microwave background. The cosmic microwave background demarks the point beyond which we can never observe. It is like the barrier beyond which your headlamp just can’t reach when scuba diving, or that place in the fog your candle cannot illuminate because it’s just too far away. Our universe, within this shell, is 93 billion light years across, but what we can see is likely no more than a few percent of the whole. But it is all the universe we will ever know. We live on just one small pale blue dot orbiting a metal rich star. We exist because matter and anti matter were formed in unequal parts. We exist because the universe’s density was just right. We exist, because other stars formed, created heavy elements, and died, distributing the elements back into space to form our world and others. And most amazingly of all, we live in a universe that is at once something we can learn to understand and something that is beyond our imagining. Every day we are finding new things that defy our theories and force us to expand our ideas – We now know 26% of the universe is made of dark matter – a material like nothing experienced here on earth – and 70% of the universe is contained in dark energy – something we know so little about all we can really do is say we have a name for this rather large blank are in our scientific understanding. And every day we discover new planets in places we never imaged. New galaxies. New types of objects – all things we would have never imagined in our wildest science fiction. The most amazing thing about science is that it works, and through its equations and rules we can build an understanding a universe that it beyond the ability of a single man or woman to full understand and visualize. Our universe is vast and old, and we are but small fragile creature brief in our time on this earth. But for all our smallness, we do understand our universe through science. In this show I only had 10 minutes to tell you about our small place in space. If you’d like to learn more, please tune in to Astronomy Cast with Fraser Cain and myself, or read my blog at starstryder.com End of podcast: 365 Days of Astronomy ===================== The 365 Days of Astronomy Podcast is produced by the Astrosphere New Media Association. Audio post-production by Preston Gibson. Bandwidth donated by libsyn.com and wizzard media. Web design by Clockwork Active Media Systems. You may reproduce and distribute this audio for non-commercial purposes. Please consider supporting the podcast with a few dollars (or Euros!). Visit us on the web at 365DaysOfAstronomy.org or email us at info@365DaysOfAstronomy.org. Until tomorrow...goodbye.]]> http://365daysofastronomy.org/2012/05/12/may-12th-encore-our-place-in-space/feed/ 0 podcast iya 365 Date: May 12, 2012 - Title: Encore: Our Place in Space - Podcaster: Pamela Gay - Organization: Astronomy Cast, Star Stryder - This podcast originally aired on May 18th, 2010 http://365daysofastronomy.org/2010/05/18/may-18th-our-place-in-space/ - Date: May 12, 2012 Title: Encore: Our Place in Space Podcaster: Pamela Gay Organization: Astronomy Cast, Star Stryder This podcast originally aired on May 18th, 2010 http://365daysofastronomy.org/2010/05/18/may-18th-our-place-in-space/ Description: From the surface of the Earth, it is easy to feel safe, and in control because we have the knowledge to understand the universe. But we are small, and life is fragile in this vast universe, and there are more things in heaven and earth waiting to be discovered than are dreamt of in all our sciences. In this podcast I try and provide context on both out place in time and in space, and just how fragile our human existence really is. Bio: Dr. Pamela Gay is a professor at Southern Illinois University-Edwardsville. She is also an astronomer, writer, and podcaster focused on using new media to engage people in science and technology. Listen to her weekly on one of the most popular astronomy podcasts, Astronomy Cast. Follow her on her blog, Star Stryder. Sponsor:This episode of 365 days of astronomy was sponsored by iTelescope.net - Expanding your horizons in astronomy today. The premier on-demand telescope network, at dark sky sites in Spain, New Mexico and Siding Spring, Australia. Transcript: Welcome to 365 Days of Astronomy. This is Pamela Gay of Astronomy Cast and StarStryder.com coming to you from Southern Illinois. On this Rainy spring day it seems like all the world is in my backyard, and most of it is triggering hay fever. The truth is, h ere on the surface of the Earth it is easy to see our universe as small and understood. Each year the seasons tick past in explainable ways, and 400 years after Kepler, the motion of the planets is just something we take for granted. Solar eclipses no longer make people tremble as the Asseryians trembled on the battlefield during the 763BC, instead the tremble in anticipation of the perfect picture during the astronomical eclipse tours. Today eclipses are just a roughly twice a year things that thousands of people turn into vacations. From the surface of the Earth, it is easy to feel safe, and in control because we have the knowledge to understand the universe. We have science to explain the supernovae, the comets, the every twinkle and gleam in the sky. But we are small, and life is fragile in this vast universe, and there are more things in heaven and earth waiting to be discovered than are dreamt of in all our sciences. Our human minds struggles to grasp at the scale of our universe. Any number over a million is simply large, and in discussing the cosmos, we discuss the billions and billions of galaxies, the billions and billions of stars, and distances so vaste that light has not yet had time to travel from most distant galaxies we see in the north to the most distant galaxies we see in our Southern skies. In this universe defined by unimaginable billions, it is easy to lose track of our place in the context of space. Carl Sagan referred to the earth as a Pale Blue Dot and in images taken by the Cassini space probe as orbited Saturn, we can see the distant Earth in its smallness. Sagan wrote of our world, “Look again at that dot. That’s here, that’s home, that’s us. On it everyone you love, everyone you know, everyone you ever heard of, every human being who ever was, lived out their lives. The aggregate of our joy and suffering, thousands of confident religions, ideologies, and economic doctrines, … every king and peasant, every young couple in love, every mother and father, hopeful child, inventor and explorer, every teacher of morals, every corrupt politician, every ’superstar,’ every ’supreme leader,’ every saint and sinner in the history of our species lived there – on a mote of dust suspended in a sunbeam.” Sagan worked to express our smallness, but this isn’t our only struggle. We also struggle to understand our place in the vastness of time. 365 Days of Astronomy no May 11th: Take Mercury for a Spin http://365daysofastronomy.org/2012/05/11/may-11th-take-mercury-for-a-spin/ http://365daysofastronomy.org/2012/05/11/may-11th-take-mercury-for-a-spin/#comments Fri, 11 May 2012 12:03:58 +0000 kortney.hogan http://365daysofastronomy.org/?p=7672 Date: May 11, 2012 Title: Take Mercury for a Spin Podcaster: Bob Hirshon Organization: American Association for the Advancement of Science (AAAS) Links: http://www.aaas.org Description: The Google Earth platform is useful for more than just checking out Earth-bound topography and features. AAAS Science Update host Bob Hirshon spoke with ace programmer Jason Smith, of Silicon Valet, about how he converts raw image data of the planet Mercury taken by the MESSENGER spacecraft into KML files that map the imagery onto the Google Earth sphere. The result? A detailed Mercury globe that anyone can take for a spin. Bio: Bob Hirshon is Senior Project Director at the American Association for the Advancement of Science (AAAS) and host of the daily radio show and podcast Science Update. Now in its 24th year, Science Update is heard on over 300 commercial stations nationwide. Hirshon also heads up Kinetic City, including the Peabody Award winning children’s radio drama, McGraw-Hill book series and Codie Award winning website and education program. He oversees the Science NetLinks project for K-12 science teachers, part of the Verizon Foundation Thinkfinity partnership. Hirshon is a Computerworld/ Smithsonian Hero for a New Millennium laureate. Sponsor: "This episode of 365 Days of Astronomy is sponsored by The Education and Outreach team for the MESSENGER mission to planet Mercury. Follow the mission as the spacecraft helps to unlock the secrets of the inner solar system at www.messenger-education.org" "Additional sponsorship for this episode of 365 days of astronomy was provided by iTelescope.net - Expanding your horizons in astronomy today. The premier on-demand telescope network, at dark sky sites in Spain, New Mexico and Siding Spring, Australia." Transcript: *** Transcript coming soon. *** End of podcast: 365 Days of Astronomy ===================== The 365 Days of Astronomy Podcast is produced by the Astrosphere New Media Association. Audio post-production by Preston Gibson. Bandwidth donated by libsyn.com and wizzard media. Web design by Clockwork Active Media Systems. You may reproduce and distribute this audio for non-commercial purposes. Please consider supporting the podcast with a few dollars (or Euros!). Visit us on the web at 365DaysOfAstronomy.org or email us at info@365DaysOfAstronomy.org. Until tomorrow...goodbye.]]> http://365daysofastronomy.org/2012/05/11/may-11th-take-mercury-for-a-spin/feed/ 0 podcast iya 365 Date: May 11, 2012 - Title: Take Mercury for a Spin - Podcaster: Bob Hirshon - Organization: American Association for the Advancement of Science (AAAS) - Links: http://www.aaas.org - Description: The Google Earth platform is useful for more than ... Date: May 11, 2012 Title: Take Mercury for a Spin Podcaster: Bob Hirshon Organization: American Association for the Advancement of Science (AAAS) Links: http://www.aaas.org Description: The Google Earth platform is useful for more than just checking out Earth-bound topography and features. AAAS Science Update host Bob Hirshon spoke with ace programmer Jason Smith, of Silicon Valet, about how he converts raw image data of the planet Mercury taken by the MESSENGER spacecraft into KML files that map the imagery onto the Google Earth sphere. The result? A detailed Mercury globe that anyone can take for a spin. Bio: Bob Hirshon is Senior Project Director at the American Association for the Advancement of Science (AAAS) and host of the daily radio show and podcast Science Update. Now in its 24th year, Science Update is heard on over 300 commercial stations nationwide. Hirshon also heads up Kinetic City, including the Peabody Award winning children’s radio drama, McGraw-Hill book series and Codie Award winning website and education program. He oversees the Science NetLinks project for K-12 science teachers, part of the Verizon Foundation Thinkfinity partnership. Hirshon is a Computerworld/ Smithsonian Hero for a New Millennium laureate. Sponsor: "This episode of 365 Days of Astronomy is sponsored by The Education and Outreach team for the MESSENGER mission to planet Mercury. Follow the mission as the spacecraft helps to unlock the secrets of the inner solar system at www.messenger-education.org" "Additional sponsorship for this episode of 365 days of astronomy was provided by iTelescope.net - Expanding your horizons in astronomy today. The premier on-demand telescope network, at dark sky sites in Spain, New Mexico and Siding Spring, Australia." Transcript: *** Transcript coming soon. *** End of podcast: 365 Days of Astronomy ===================== The 365 Days of Astronomy Podcast is produced by the Astrosphere New Media Association. Audio post-production by Preston Gibson. Bandwidth donated by libsyn.com and wizzard media. Web design by Clockwork Active Media Systems. You may reproduce and distribute this audio for non-commercial purposes. Please consider supporting the podcast with a few dollars (or Euros!). Visit us on the web at 365DaysOfAstronomy.org or email us at info@365DaysOfAstronomy.org. Until tomorrow...goodbye. 365 Days of Astronomy no May 10th: Twinkle Twinkle little star …… How I wonder FS Aur? http://365daysofastronomy.org/2012/05/10/may-10th-twinkle-twinkle-little-star-how-i-wonder-fs-aur/ http://365daysofastronomy.org/2012/05/10/may-10th-twinkle-twinkle-little-star-how-i-wonder-fs-aur/#comments Thu, 10 May 2012 11:00:04 +0000 kortney.hogan http://365daysofastronomy.org/?p=7652 Date: May 10, 2012 Title: Twinkle Twinkle little star ...... How I wonder FS Aur? Podcaster: Peter Lake Organization: AARTScope Blog Links: http://aartscope.blogspot.com http://vitaly.neustroev.net/research/observing-campaigns/ http://www.twitter.com/fs_Aur http://www.aavso.org Description: FS Aur is one of the most strangest and erratic variable Stars. Peter Lake reports on the data collected as part of the broader work with Dr Vitaly Neustroev of the Oulu University Finland and discusses the past two seasons of observations. Peter Lake is an Amateur Astronomer from Melbourne Australia and regularly discusses how people can be involved in citizen science and observation programs. Bio: Peter Lake is an amateur Astronomer from Melbourne, Australia, a member of Variable Stars South and the AAVSO and he owns and operates a 0.5m Planewave CDK Telescope at New Mexico skies, which is affiliated to iTelescope.net. Peter has been a participant in citizen science and recovered asteroid 2000 EV70 during the Spacewatch FMO program. More recently Peter has been actively involved in the study of cataclysmic variable star FS Aur, and followup exoplanet observations on Kepler targets of interest. Sponsor: "This episode of 365 days of astronomy is sponsored with thanks to all non-US contributors for showing us that the night sky is something we can all share." "Additional sponsorship for this episode of 365 days of astronomy was provided by iTelescope.net - Expanding your horizons in astronomy today. The premier on-demand telescope network, at dark sky sites in Spain, New Mexico and Siding Spring, Australia." Transcript: Like duck hunting, Variable Stars have their "Seasons" also. A season being where the variable star in question is in the optimal position for "shooting with CCDs" ie observable for most of the night, during this time ideally it can be visible for as many as 6-7 hours per night. FS Aur is a Cataclysmic Variable is now low in the west at sunset at the close of an intensive second season. So I though it would be good to review these past two seasons, before once again, it comes around for observations in the next northern winter. FS Aur is one of the strangest and complex objects in the extensive variable star family. It is thought to be a magnetic white dwarf and red giant binary Star with a third object acting on it in a circumbinary orbit. (Tovmassian et al., 2010) Back in 2010 there was a sporadic and incomplete light curve and astronomers wanted answers. When they want answers they often leverage the collective effort of the American Association of Variable Star Observers (AAVSO), to muscle up some more observations and data. FS Aur has a number of photometric and spectroscopic cycles going on. On top of this it goes into outburst about every 12-15 days. The outburst duration is so short (2-3 days) it has been regularly missed in the past - so in the 2010/11 season Dr Neustroev rallied a special effort. For the first time, members of the AAVSO mapped the entire outburst cycle, a good number of times. Dr Vitaly Neustroev is the University Researcher (Yliopistotutkija) at the University of Oulu, Finland and he is a key researcher on FS Aur, working hard to better understand its erratic behaviour. Visit the observing campaign page here, and also follow on (Twitter). I like following Cataclysmic Variables, after catching Simostronomy fever, and I have been a regular on FS Aur since Dr Neustroev's call to action. During the campaign FS Aur has been dancing away with a little periodic wobble at about 15.9 with the odd subtle change in brightness, then it goes really dull to 16.2 then literally within 24-36 hours it pops up to magnitude about Mag 14. As an amateur astronomer I am always careful to point out that I'm not qualified to say how or why, but I can tell you when, where and how bright! So what is going on with FS Aur - Dr Neustroev describes it this way: “FS Aur is an extremely unusual cataclysmic variable renown for the presence of a variety of uncommon and largely incomprehensible periodic variabilities of brightness and radial velocity. The outlandish peculiarity of FS Aur is the existence of a very coherent photometric period of 205.5 min that exceeds the spectroscopic orbital period of 85.7 minutes by 2.4 times. Such a discrepancy in the photometric and spectroscopic periods is highly unusual for cataclysmic variables. Based on the short orbital period, FS Aur has been classified as a SU UMa star. Nevertheless, long‐term monitoring of the system by several groups failed to detect any superoutburst in its light curve. The publicly available AAVSO light curve show instead a steady‐cyclic outburst pattern that is more similar to a SS Cyg–type dwarf nova light curve. However, this monitoring reveals an additional, discordant, and very long photometric period of ~900 days. We explain the latter by the result of eccentricity modulation of a close binary orbit induced by the presence of a third body on a circumbinary orbit (Tovmassian et al., 2010).” So it is indeed a complex beast. When variables are in season you can get nice long lightcurves and do time-series analysis and this is very valuable data. During the season I submitted some thousands of observations in V filter and color times-series in BVRI as this is also useful data. So this is indeed a fascinating object and could indeed be a new class of object. Only time will tell. AAVSO members are playing an important role in gathering the data to refine the lightcurve. Once the observing campaign is complete we await with interest to see what the astronmers and astrophysicists can tell about what they have learned. At AARTScope my mission is to "keep creating the sense of anticipation and discovery that keeps scientists asking questions" so if you are an AAVSO member and would like to join the campaign, please do. Unlike ducks, no variable stars are harmed during "peak season". So now we turn our attention to the 2011/12 season where FS Aur just gets weirder and weirder. Just when you think you've seen it all, there is always something new in Astronomy. The world of variable stars and in particular - Cataclysmic Variables, is no exception. As the 2011/12 season open in the northern winter Vitaly Neustroev released his awaited paper on the data from the 2010/11 season. The highlight for me, is of course my name included as a co-author for my first paper.....its been a long journey from hearing an Astronomy Cast podcast about science papers and how amateurs can be involved, to having my name at the top of a paper along with some of the greats of Variable Star research. (Thanks for the inspiration Pamela and Fraser & to Mike Simonsen for his mentorship as an AAVSO member). The winter campaign of 2010-2011 gathered over 14,000 individual observations in the "V" band, and many more in B,R,I from over 41 observers around the world in an exemplary collaboration effort between professional astronomers, amateurs, and AAVSO members. The 2011/12 campaign has focus less on the color variations in the various BVRI filters, but more closer focus on what going on whilst the system is in quiescence. Previously Tovmassian et al had established that FS Aur has a long photomentric period of 205.5 mins that exceeds the Spectroscopic orbital period of 85.7 mins by 2.4 times. A second long spectroscopic period of 147 minutes was also discovered and Tovmassian et al (2007) suggested that this was evidence of a third body in circumbinary orbit. The purpose of the 2010-2011 was to gather more data and photometrically confirm the specroscopic data. Vitaly's paper now add to Tovmassian's work. In summary, the observations found a modulation in the B-I Color index, and for the first time the precession period for the White Dwarf was identified from photmetric data, and confirmed the previous spectroscopic data. I asked Vitaly about the significance of the findings:

"Should the free precession be accepted as the correct explanation of the phenomena, it will give an important tool to study white dwarf equations of state. The theory of compact objects predicts certain relations between the spin and precession periods, and our finding provides a good test for the theory and establishes a qualitative model to be explored both theoretically and observationally. Detection of precession can become a powerful tool in searching for the internal properties of compact stars, which would be otherwise inaccessible for us. Combined with other methods to estimate masses and density of the WDs in CVs, the precession period will help to refine these values, which in turn, allows for testing and proving the theory for the precession of compact stars and may allow for further advances in our knowledge of the structure of WDs and the influence of accretion on them."

Some interesting things were also observed in the quiescent state prompting additional scrutiny during this year's season of the longer term behaviour of the system when at quiescence. It has been great to be a part of the wonderful science research that is still ongoing. Its all part of the great science you can do as a part of any number of citizen science initiatives. The AAVSO and Variable Stars South have many and varied research projects just like this one where you can play a significant part in gathering the data and working with professional astronomers. It was great working with such professional people ably lead by Vitaly and George Sjoberg. Participation in campaigns like this is a great way to get to know other astronomers, and build your credibility as a capable amateur astronomer. End of podcast: 365 Days of Astronomy ===================== The 365 Days of Astronomy Podcast is produced by the Astrosphere New Media Association. Audio post-production by Preston Gibson. Bandwidth donated by libsyn.com and wizzard media. Web design by Clockwork Active Media Systems. You may reproduce and distribute this audio for non-commercial purposes. Please consider supporting the podcast with a few dollars (or Euros!). Visit us on the web at 365DaysOfAstronomy.org or email us at info@365DaysOfAstronomy.org. Until tomorrow...goodbye.]]> http://365daysofastronomy.org/2012/05/10/may-10th-twinkle-twinkle-little-star-how-i-wonder-fs-aur/feed/ 0 podcast iya 365 Date: May 10, 2012 - Title: Twinkle Twinkle little star ...... How I wonder FS Aur? - Podcaster: Peter Lake - Organization: AARTScope Blog - Links: http://aartscope.blogspot.com http://vitaly.neustroev.net/research/observing-campaigns/ http://www. Date: May 10, 2012 Title: Twinkle Twinkle little star ...... How I wonder FS Aur? Podcaster: Peter Lake Organization: AARTScope Blog Links: http://aartscope.blogspot.com http://vitaly.neustroev.net/research/observing-campaigns/ http://www.twitter.com/fs_Aur http://www.aavso.org Description: FS Aur is one of the most strangest and erratic variable Stars. Peter Lake reports on the data collected as part of the broader work with Dr Vitaly Neustroev of the Oulu University Finland and discusses the past two seasons of observations. Peter Lake is an Amateur Astronomer from Melbourne Australia and regularly discusses how people can be involved in citizen science and observation programs. Bio: Peter Lake is an amateur Astronomer from Melbourne, Australia, a member of Variable Stars South and the AAVSO and he owns and operates a 0.5m Planewave CDK Telescope at New Mexico skies, which is affiliated to iTelescope.net. Peter has been a participant in citizen science and recovered asteroid 2000 EV70 during the Spacewatch FMO program. More recently Peter has been actively involved in the study of cataclysmic variable star FS Aur, and followup exoplanet observations on Kepler targets of interest. Sponsor: "This episode of 365 days of astronomy is sponsored with thanks to all non-US contributors for showing us that the night sky is something we can all share." "Additional sponsorship for this episode of 365 days of astronomy was provided by iTelescope.net - Expanding your horizons in astronomy today. The premier on-demand telescope network, at dark sky sites in Spain, New Mexico and Siding Spring, Australia." Transcript: Like duck hunting, Variable Stars have their "Seasons" also. A season being where the variable star in question is in the optimal position for "shooting with CCDs" ie observable for most of the night, during this time ideally it can be visible for as many as 6-7 hours per night. FS Aur is a Cataclysmic Variable is now low in the west at sunset at the close of an intensive second season. So I though it would be good to review these past two seasons, before once again, it comes around for observations in the next northern winter. FS Aur is one of the strangest and complex objects in the extensive variable star family. It is thought to be a magnetic white dwarf and red giant binary Star with a third object acting on it in a circumbinary orbit. (Tovmassian et al., 2010) Back in 2010 there was a sporadic and incomplete light curve and astronomers wanted answers. When they want answers they often leverage the collective effort of the American Association of Variable Star Observers (AAVSO), to muscle up some more observations and data. FS Aur has a number of photometric and spectroscopic cycles going on. On top of this it goes into outburst about every 12-15 days. The outburst duration is so short (2-3 days) it has been regularly missed in the past - so in the 2010/11 season Dr Neustroev rallied a special effort. For the first time, members of the AAVSO mapped the entire outburst cycle, a good number of times. Dr Vitaly Neustroev is the University Researcher (Yliopistotutkija) at the University of Oulu, Finland and he is a key researcher on FS Aur, working hard to better understand its erratic behaviour. Visit the observing campaign page here, and also follow on (Twitter). I like following Cataclysmic Variables, after catching Simostronomy fever, and I have been a regular on FS Aur since Dr Neustroev's call to action. During the campaign FS Aur has been dancing away with a little periodic wobble at about 15.9 with the odd subtle change in brightness, then it goes really dull to 16.2 then literally within 24-36 hours it pops up to magnitude about Mag 14. As an amateur astronomer I am always careful to point out that I'm not qualified to say how or why, but I can tell you when, where and how bright! So what is going on with FS Aur - Dr Neustroev describes it this way: 365 Days of Astronomy no May 9th: Astronomy Word of the Week: Nova http://365daysofastronomy.org/2012/05/09/may-9th-astronomy-word-of-the-week-nova/ http://365daysofastronomy.org/2012/05/09/may-9th-astronomy-word-of-the-week-nova/#comments Wed, 09 May 2012 11:00:09 +0000 kortney.hogan http://365daysofastronomy.org/?p=7650 Date: May 9, 2012 Title: Astronomy Word of the Week: Nova Podcaster: Dr. Christopher Crockett Organization: United States Naval Observatory Links: http://christophercrockett.com http://astrowow.wordpress.com/ Description: Why do once invisible stars suddenly flare up and then slowly fade from view? The astronomy word of the week is "nova". Bio: Dr. Christopher Crockett is an astronomer at the United States Naval Observatory in Flagstaff, Arizona. His research involves searching for planets around very young stars (“only” a few million years old). It is hoped that the results from this research will help constrain models of planet formation and lead to a better understanding of where, when, and how often planets form. Chris is also passionate about astronomy outreach and education and will talk for hours about the Universe if you let him. Sponsors: Sponsorship for this episode of "365 days of Astronomy" is donated anonymously and dedicated to the men and women of NASA who strive to turn science fiction into science reality. Additional sponsorship for this episode has been provided by iTelescope.net - Expanding your horizons in astronomy today. The premier on-demand telescope network, at dark sky sites in Spain, New Mexico and Siding Spring, Australia. Transcript: In 1572, Danish astronomer Tycho Brahe, along with observers around the world, noticed a new star in the constellation Casseiopeia. Rivaling Venus as the brightest object in the night sky after the Moon, the unexpected guest remained visible for nearly two years before fading from view. The appearance of a new star was nothing short of revolutionary; astronomers long agreed that the celestial sphere was unchanging. A transient star challenged this assumption and suggested that the heavens were perhaps more dynamic than originally thought. The celestial intruder came to be known as a "nova" - after Tycho Brahe's extensive manuscript on the phenomenon - where he referred to the object simply by the latin term for a new star: "stella nova". While no one could have known it at the time, the new star was actually not new at all but rather a very old star experiencing a cataclysmic event. Most of the stars in the sky are not singular, like our Sun, but rather members of binary star systems - two stars locked in orbit around one another. Of this pair, one star is often more massive than its companion and therefore burns through its nuclear fuel at a faster rate. The heavier star reaches the end of its life before its sibling. When it does, the star inflates to become a red giant and sheds its outer layers into space leaving behind the hot, dense stellar core. The naked core, known as a "white dwarf", continues to orbit its stellar neighbor while taking the next few billion years to passively cool from a white-hot 100,000 degrees. In the case of close binary pairs, the white dwarf can actually siphon matter off of its companion. The intermingled gravitational fields of the two stars builds a bridge of predominately hydrogen gas spanning the distance between them. Gas from the still active star flows through this gravitational funnel and spills on to the surface of the white dwarf. The mass of the white dwarf controls the rate of mass accretion; if the rate is high enough, then something quite spectacular can happen. White dwarfs are an example of a rather exotic type of matter that physicists call "degenerate". Most gasses expand when you heat them up: the increasing temperature causes the molecules to zip around faster which in turn increases the gas pressure. At extreme densities - like those seen in the cores of stars - the gas behaves rather peculiarly. The pressure is no longer a slave to temperature: turn up the heat and the gas does not expand. This counterintuitive behavior is crucial to what happens next on the white dwarf's surface. As hydrogen from the donor star comes crashing down, the crushing force of gravity compresses it into a degenerate state and the intense radiation heats the gas to many millions of degrees. But having now obtained the properties of a degenerate gas, the newly acquired hydrogen shell doesn't expand in response to the rapid heating, but holds its pressure steady. And now things get interesting. At temperatures exceeding 16 million degrees Celsius, conditions on the surface mimic those deep in the cores of stars and a thermonuclear explosion is the result. Hydrogen is rapidly fused into helium and the resulting release of energy blows the outer hydrogen shell off the surface of the white dwarf at speeds exceeding ten million kilometers per hour. In mere days, the white dwarf can increase its brightness by 100,000 times. It can then take months - or in some cases years - for the star to slowly fade from view. Our Milky Way Galaxy experiences several dozen novae each year, only about ten of which are visible from Earth. A few are even visible to the naked eye. The most recent nova to be seen without the aid of binoculars or telescopes did so in the constellation Scorpius, reaching its peak brightness on February 17, 2007. Even more rare are what astronomers call "recurrent nova". Once the white dwarf has blown the hydrogen shell into space, the gas can slowly start building up again. These are novae that flare up repeatedly, sometimes once a year, sometimes once every couple of decades. In our whole galaxy, only ten novae are known to be recurrent. In the centuries since the new star of 1572, astronomers have come to realize that the event which gave novae their name was not what we know now as a nova. Up until early in the 20th century, a nova referred to any rapid brightening of a star. But there are many reasons stars suddenly flare into view. What Tycho saw was actually something far more powerful - a type of, aptly named, supernova. The supernova of 1572 was not the result of a flash of hydrogen burning on a white dwarf shell, but rather was caused by the complete detonation of a white dwarf. By stealing gas from a nearby companion slowly enough, the progenitor of the supernova delayed a nova flash while gradually increasing its temperature and pressure and eventually igniting hydrogen fusion throughout the interior of the once dead stellar core. With out the counterbalancing force of the rest of the star to throttle these reactions, the now violently active core obliterated itself in one of the most powerful explosions the Universe can produce. The event of 1572 ushered in a new era of astronomy, one in which the constancy of the celestial sphere could no longer be assumed. Novae - and their more powerful supernovae cousins - are constant reminders that we, in fact, live in a highly dynamic and energetic Universe. End of podcast: 365 Days of Astronomy ===================== The 365 Days of Astronomy Podcast is produced by the Astrosphere New Media Association. Audio post-production by Preston Gibson. Bandwidth donated by libsyn.com and wizzard media. Web design by Clockwork Active Media Systems. You may reproduce and distribute this audio for non-commercial purposes. Please consider supporting the podcast with a few dollars (or Euros!). Visit us on the web at 365DaysOfAstronomy.org or email us at info@365DaysOfAstronomy.org. Until tomorrow...goodbye.]]> http://365daysofastronomy.org/2012/05/09/may-9th-astronomy-word-of-the-week-nova/feed/ 0 podcast iya 365 Date: May 9, 2012 - Title: Astronomy Word of the Week: Nova - Podcaster: Dr. Christopher Crockett - Organization: United States Naval Observatory - Links: http://christophercrockett.com http://astrowow.wordpress.com/ - Date: May 9, 2012 Title: Astronomy Word of the Week: Nova Podcaster: Dr. Christopher Crockett Organization: United States Naval Observatory Links: http://christophercrockett.com http://astrowow.wordpress.com/ Description: Why do once invisible stars suddenly flare up and then slowly fade from view? The astronomy word of the week is "nova". Bio: Dr. Christopher Crockett is an astronomer at the United States Naval Observatory in Flagstaff, Arizona. His research involves searching for planets around very young stars (“only” a few million years old). It is hoped that the results from this research will help constrain models of planet formation and lead to a better understanding of where, when, and how often planets form. Chris is also passionate about astronomy outreach and education and will talk for hours about the Universe if you let him. Sponsors: Sponsorship for this episode of "365 days of Astronomy" is donated anonymously and dedicated to the men and women of NASA who strive to turn science fiction into science reality. Additional sponsorship for this episode has been provided by iTelescope.net - Expanding your horizons in astronomy today. The premier on-demand telescope network, at dark sky sites in Spain, New Mexico and Siding Spring, Australia. Transcript: In 1572, Danish astronomer Tycho Brahe, along with observers around the world, noticed a new star in the constellation Casseiopeia. Rivaling Venus as the brightest object in the night sky after the Moon, the unexpected guest remained visible for nearly two years before fading from view. The appearance of a new star was nothing short of revolutionary; astronomers long agreed that the celestial sphere was unchanging. A transient star challenged this assumption and suggested that the heavens were perhaps more dynamic than originally thought. The celestial intruder came to be known as a "nova" - after Tycho Brahe's extensive manuscript on the phenomenon - where he referred to the object simply by the latin term for a new star: "stella nova". While no one could have known it at the time, the new star was actually not new at all but rather a very old star experiencing a cataclysmic event. Most of the stars in the sky are not singular, like our Sun, but rather members of binary star systems - two stars locked in orbit around one another. Of this pair, one star is often more massive than its companion and therefore burns through its nuclear fuel at a faster rate. The heavier star reaches the end of its life before its sibling. When it does, the star inflates to become a red giant and sheds its outer layers into space leaving behind the hot, dense stellar core. The naked core, known as a "white dwarf", continues to orbit its stellar neighbor while taking the next few billion years to passively cool from a white-hot 100,000 degrees. In the case of close binary pairs, the white dwarf can actually siphon matter off of its companion. The intermingled gravitational fields of the two stars builds a bridge of predominately hydrogen gas spanning the distance between them. Gas from the still active star flows through this gravitational funnel and spills on to the surface of the white dwarf. The mass of the white dwarf controls the rate of mass accretion; if the rate is high enough, then something quite spectacular can happen. White dwarfs are an example of a rather exotic type of matter that physicists call "degenerate". Most gasses expand when you heat them up: the increasing temperature causes the molecules to zip around faster which in turn increases the gas pressure. At extreme densities - like those seen in the cores of stars - the gas behaves rather peculiarly. The pressure is no longer a slave to temperature: turn up the heat and the gas does not expand. This counterintuitive behavior is crucial to what happens next on the white dwarf's surface. As hydrogen from the donor star comes crashing down, 365 Days of Astronomy no May 8th: What is Black http://365daysofastronomy.org/2012/05/08/may-8th-what-is-black/ http://365daysofastronomy.org/2012/05/08/may-8th-what-is-black/#comments Tue, 08 May 2012 11:00:41 +0000 kortney.hogan http://365daysofastronomy.org/?p=7646 Date: May 8, 2012 Title: What is Black Podcaster: Rob Sparks & Dr. Steven Pompea Organization: NOAO Links: www.noao.edu Description: Most people think of black as a color, but black is really the absence of light. Truly black surfaces reflect almost none of the light that falls on them. In this podcast, Dr. Stephen Pompea discusses black surface, how they are produced and why they are important in astronomy and other sciences. Bio: Rob Sparks is a science education specialist in the EPO group at NOAO and works on the Galileoscope project (www.galileoscope.org), providing design, dissemination and professional development. He also pens a great blog at halfastro.wordpress.com. Dr. Stephen Pompea did his undergraduate work in physics, space physics, and astronomy at Rice University, his Master’s work in physics teaching at Colorado State University, and his Ph.D. in astronomy at the University of Arizona. He is currently the manager of the Education and Public Outreach Group at the National Optical Astronomy Observatory. Sponsor: This episode of the 365 Days of Astronomy podcast is sponsored by the National Optical Astronomy Observatory. NOAO is a US national research and development center for ground-based nighttime astronomy. We provide astronomers access to world-class observing facilities on a peer-reviewed basis. Our mission is to engage in programs to develop the next generation of telescopes, instruments, and software tools necessary to enable exploration and investigation through the observable Universe. For information on observing proposals or our public programs, please visit www.noao.edu for more information. "This episode has also been sponsored by the Lake County Astronomical Society: Celebrating 30 years of stellar service to members and the public." Transcript: *** Transcript coming soon. *** End of podcast: 365 Days of Astronomy ===================== The 365 Days of Astronomy Podcast is produced by the Astrosphere New Media Association. Audio post-production by Preston Gibson. Bandwidth donated by libsyn.com and wizzard media. Web design by Clockwork Active Media Systems. You may reproduce and distribute this audio for non-commercial purposes. Please consider supporting the podcast with a few dollars (or Euros!). Visit us on the web at 365DaysOfAstronomy.org or email us at info@365DaysOfAstronomy.org. Until tomorrow...goodbye.]]> http://365daysofastronomy.org/2012/05/08/may-8th-what-is-black/feed/ 0 podcast iya 365 Date: May 8, 2012 - Title: What is Black - Podcaster: Rob Sparks & Dr. Steven Pompea - Organization: NOAO - Links: www.noao.edu - Description: Most people think of black as a color, but black is really the absence of light. Date: May 8, 2012 Title: What is Black Podcaster: Rob Sparks & Dr. Steven Pompea Organization: NOAO Links: www.noao.edu Description: Most people think of black as a color, but black is really the absence of light. Truly black surfaces reflect almost none of the light that falls on them. In this podcast, Dr. Stephen Pompea discusses black surface, how they are produced and why they are important in astronomy and other sciences. Bio: Rob Sparks is a science education specialist in the EPO group at NOAO and works on the Galileoscope project (www.galileoscope.org), providing design, dissemination and professional development. He also pens a great blog at halfastro.wordpress.com. Dr. Stephen Pompea did his undergraduate work in physics, space physics, and astronomy at Rice University, his Master’s work in physics teaching at Colorado State University, and his Ph.D. in astronomy at the University of Arizona. He is currently the manager of the Education and Public Outreach Group at the National Optical Astronomy Observatory. Sponsor: This episode of the 365 Days of Astronomy podcast is sponsored by the National Optical Astronomy Observatory. NOAO is a US national research and development center for ground-based nighttime astronomy. We provide astronomers access to world-class observing facilities on a peer-reviewed basis. Our mission is to engage in programs to develop the next generation of telescopes, instruments, and software tools necessary to enable exploration and investigation through the observable Universe. For information on observing proposals or our public programs, please visit www.noao.edu for more information. "This episode has also been sponsored by the Lake County Astronomical Society: Celebrating 30 years of stellar service to members and the public." Transcript: *** Transcript coming soon. *** End of podcast: 365 Days of Astronomy ===================== The 365 Days of Astronomy Podcast is produced by the Astrosphere New Media Association. Audio post-production by Preston Gibson. Bandwidth donated by libsyn.com and wizzard media. Web design by Clockwork Active Media Systems. You may reproduce and distribute this audio for non-commercial purposes. Please consider supporting the podcast with a few dollars (or Euros!). Visit us on the web at 365DaysOfAstronomy.org or email us at info@365DaysOfAstronomy.org. Until tomorrow...goodbye. 365 Days of Astronomy no May 7th: The Late Heavy Bombardment — an Extended Version? http://365daysofastronomy.org An astronomy podcast every day, all year Wed, 16 May 2012 11:00:41 +0000 en hourly 1 http://wordpress.org/?v=3.1 An astronomy podcast every day, all year 365 Days of Astronomy no An astronomy podcast every day, all year 365 Days of Astronomy http://365daysofastronomy.org An astronomy podcast every day, all year Wed, 16 May 2012 11:00:41 +0000 en hourly 1 http://wordpress.org/?v=3.1 An astronomy podcast every day, all year 365 Days of Astronomy no An astronomy podcast every day, all year 365 Days of Astronomy http://365daysofastronomy.org/wp-content/plugins/powerpress/rss_default.jpg http://365daysofastronomy.org May 16th: GPS http://365daysofastronomy.org/2012/05/16/may-16th-gps/ http://365daysofastronomy.org/2012/05/16/may-16th-gps/#comments Wed, 16 May 2012 11:00:41 +0000 kortney.hogan http://365daysofastronomy.org/?p=7689 Date: May 16, 2012 Title: GPS Podcaster: Steve Nerlich Organization: Cheap Astronomy Links: www.cheapastro.com Description: Cheap Astronomy once again demonstrates that pretty much everything in life has a connection to astronomy. Bio: Cheap Astronomy offers an educational website because in space no-one can hear you podcast. Today's Sponsor: "This episode of 365 days of Astronomy" is sponsored by the Lake County Astronomical Society: Celebrating 30 years of stellar service to members and the public." Additional sponsorship for this episode has also been provided by iTelescope.net - Expanding your horizons in astronomy today. The premier on-demand telescope network, at dark sky sites in Spain, New Mexico and Siding Spring, Australia. Transcript: Hi this is Steve Nerlich from Cheap Astronomy www.cheapastro.com and this is GPS OK – If you don’t have one, you know someone who does, so let’s skip the introductions and get straight down to the astronomy. A standard GPS configuration is a constellation of 24 GPS satellites. The satellites are all at an altitude of 20,200 km with an orbital period of 11 hours and 58 minutes – which means they do exactly 2 orbits for each time the Earth spins once on its axis. Four satellites each follow six orbital planes separated by 60 degrees which surround the Earth in an (airquotes) ‘birdcage’ of criss-crossing orbits. There a link to the relevant Wikipedia article from the Cheap Astronomy podcast page which has a nice animation of a GPS satellite constellation. At last count, there were actually 31 actively transmitting GPS satellites – with these extra number increasing location accuracy and redundancy. There’s been some recent media regarding a growing risk of dropping below the minimum 24 active satellites required to make GPS work effectively, but it remains to be seen if this risk will be realised in the face of the increasing economic importance of maintaining a working GPS system. A GPS satellite broadcasts a signal indicating where it is and the time the signal was broadcast – your receiver then determines, from the time it receives that signal, the distance travelled by the signal, knowing that, being a radio transmission, the signal travels at the speed of light. By making just four calculations from four satellites in the sky, your GPS receiver can then establish its position with respect to latitude, longitude and altitude. It’s all about the conjunction of spheres. Imagine one satellite broadcasting a radio signal. If you pick up that signal and determine it’s a 100 km away, all you really know is that you are somewhere on a surface of a sphere with a 100 km radius that has the satellite at its centre. If there’s two such satellites then you’ll know you are somewhere on the circumference of a circle representing the plane where the two spheres of radio broadcast overlap. Introduce a third satellite and you can narrow down your location to just two points in space which are the points where two differently orientated circle circumferences intersect. Potentially this may be enough to roughly determine your position since you can anticipate you will be on the one of those two points corresponding to the surface of the Earth. But for strictest accuracy – including accuracy in determining your altitude above sea level, the signal from a fourth satellite is required. And that is the idea of the constellation of GPS satellites. Keeping 24 satellites moving in the same orbit, tracing a birdcage of divergent paths around the globe ensures there will always be four satellites in the sky wherever you happen to be on Earth. Now when I say GPS satellites just have to broadcast where they are – actually knowing where they are is a whole separate operation, While the orbital period is predictable, knowing at what point they are on that orbit requires some very accurate time keeping – for which reason each satellite has an atomic clock. Nonetheless, even this isn’t enough, as the orbital paths of the satellites are subject to slight shifting due to the gravitational influence of the Sun and the Moon. To keep track of these changes the satellites are monitored from a fixed, known location on the Earth’s surface – a function currently managed by the 50th Space Wing of the US Airforce Space Command – seriously. Now, given that your GPS receiver is working out its distance from each of four satellites based solely on the time lag of a signal moving at the speed of light from a satellite just over 20,000 kilometres away – there is considerable potential for a margin of error that could see you driving over the embankment into a river when that sexy voice says ‘turn left now’. There are a range of methods to deal with various sources of error. Firstly your GPS receiver carries an electronic almanac of which satellite should be where since confusion can arise when the satellite radio signals get reflected off surroundings, such as tall buildings. This electronic almanac is constructed from calibration data received from the GPS satellites, although these data are generally relayed from a ground-based source – such as Airforce Space Command. The almanac helps your receiver distinguish between garbage signals and genuine GPS signals. The receiver also receives time checks from the satellites since, most GPS receivers determine time from a cheap (not that there’s anything wrong with that) quartz clock rather than the ultra-accurate atomic clocks of the satellites. Clock error is probably the biggest potential source of GPS error, which is why, even though you could almost get away with determining your position from just 3 satellites, it is the fourth reading (which we might call quadrangulation) that ensures the poorer accuracy of the GPS receiver’s clock is effectively accounted for. Interestingly, there’s also relativistic effects to account for, since the satellites move in a weaker gravity field (meaning by general relativity their clocks run faster), and they also move at speed relative to the surface of the Earth (meaning by special relativity their clocks run slower). It turns out that the nett effect is that the satellites’ clocks run about 38 microseconds per day faster than they would at the Earth’s surface. To account for this, the clocks are actually set to run at a slightly lower rate, to keep pace with clocks running on the Earth’s surface. In the world of atomic clocks, various time keeping callibrations are also required to account for changes in the rotation of the Earth – which is influenced by the tidal drag of the Moon , the inertia of the Earth’s molten interior and even the melting of glaciers. Overall, the Earth’s rotation is slowing, leading to a lengthening of a solar day. Consequently a leap second must be introduced to atomic timepieces which measure Universal Coordinated Time (known as UTC – because of the French). In fact, a leap second is required to be added to UTC every 18 months or so because each year (on average) the length of a solar day increases by about 0.002 seconds. The atomic clocks of GPS satellites were aligned to UTC in 1980 – but as of 2009, these atomic clocks in orbit now vary by 19 seconds and to keep it simple we just say they are running at GPS time. Various under-the-hood adjustments are made along the way so that your GPS receiver can tell you the local time wherever you happen to be – as well as telling you where you are of course to within… well, within 10 metres is the general benchmark, although this takes a few minutes to establish after the unit is turned on and the accuracy will degrade with tall trees or buildings around. So, you know, it’s a guide – not an absolute – it’s still a good idea to keep one eye on the road. Thanks for listening. This is Steve Nerlich from Cheap Astronomy, www.cheapastro.com. Cheap Astronomy offers an educational website where you can’t put a price on space. No ads, no profit, just good science. Bye. End of podcast: 365 Days of Astronomy ===================== The 365 Days of Astronomy Podcast is produced by the New Media Working Group of the International Year of Astronomy 2009. Audio post-production by Preston Gibson. Bandwidth donated by libsyn.com and wizzard media. Web design by Clockwork Active Media Systems. You may reproduce and distribute this audio for non-commercial purposes. Please consider supporting the podcast with a few dollars (or Euros!). Visit us on the web at 365DaysOfAstronomy.org or email us at info@365DaysOfAstronomy.org. Until tomorrow...goodbye.]]> http://365daysofastronomy.org/2012/05/16/may-16th-gps/feed/ 0 podcast iya 365 Date: May 16, 2012 - Title: GPS Podcaster: Steve Nerlich - Organization: Cheap Astronomy - Links: www.cheapastro.com - Description: Cheap Astronomy once again demonstrates that pretty much everything in life has a connection to astronomy. - Date: May 16, 2012 Title: GPS Podcaster: Steve Nerlich Organization: Cheap Astronomy Links: www.cheapastro.com Description: Cheap Astronomy once again demonstrates that pretty much everything in life has a connection to astronomy. B... 365 Days of Astronomy no May 15th: Astronomy Word of the Week: Obliquity http://365daysofastronomy.org/2012/05/15/may-15th-astronomy-word-of-the-week-obliquity/ http://365daysofastronomy.org/2012/05/15/may-15th-astronomy-word-of-the-week-obliquity/#comments Tue, 15 May 2012 11:00:14 +0000 kortney.hogan http://365daysofastronomy.org/?p=7687 Date: May 15, 2012 Title: Astronomy Word of the Week: Obliquity Podcaster: Dr. Christopher Crockett Organization: United States Naval Observatory Links: http://christophercrockett.com http://astrowow.wordpress.com/ Description: The tilt of our planet is about much more than the seasons. The astronomy word of the week is "obliquity". Bio: Dr. Christopher Crockett is an astronomer at the United States Naval Observatory in Flagstaff, Arizona. His research involves searching for planets around very young stars (“only” a few million years old). It is hoped that the results from this research will help constrain models of planet formation and lead to a better understanding of where, when, and how often planets form. Chris is also passionate about astronomy outreach and education and will talk for hours about the Universe if you let him. Today's Sponsor: "This episode of 365 days of Astronomy" is sponsored by iTelescope.net - Expanding your horizons in astronomy today. The premier on-demand telescope network, at dark sky sites in Spain, New Mexico and Siding Spring, Australia. This episode has also been sponsored by Lake County Astronomical Society: Celebrating 30 years of stellar service to members and the public. Transcript: The planet you're standing on is not very steady. She bobs and wobbles, ducks and weaves, as she makes her annual trek around the Sun. Our home constantly struggles with forces both external and internal; the Sun, the Moon, and the planets tug her back and forth while shifting masses within force her to constantly find new balance. The tilt of our planet's axis - what astronomers call its obliquity - is one measure of this interplanetary tug-of-war. Obliquity measures how far over a planet or moon is tipped relative to its orbit; in the Earth's case, it's about 23 degrees. We feel the obliquity in the changing seasons. In June, the north pole is tipped towards the Sun. The northern hemisphere experiences longer days and more direct sunlight giving us warm summer days. In December, the north pole is tipped away from the Sun and everyone above the equator experiences the bitter chill of winter as the days get shorter and the sunlight reaches us more obliquely. The other planets in our solar system exhibit a wide range of obliquities. Mars, Saturn, and Neptune are all tipped by roughly the same amount as Earth. Mercury and Jupiter have hardly any obliquity at all - which means no seasons for them. Venus' obliquity is 177 degrees; it is almost completely upside down. Put another way, it rotates in the opposite direction from Earth. Were there ever to be a break in Venus' stifling cloud layer, native Venusians would see the Sun rise in the west and set in the east! Uranus is another strange character; his obliquity is 97 degrees. Uranus is lying on his side! This leads to some very strange days and seasons. Each pole of Uranus alternates between being in constant sunlight for 42 years, then perpetual darkness for another 42 years. Only a very thin strip along the equator experiences anything like day/night cycles that we experience - and even then the Sun is frequently sitting very low on the horizon. Astronomers aren't entirely certain how Venus and Uranus came to have such extreme obliquities. A leading hypothesis is that both experienced massive collisions at some point in their distant past, essentially knocking them over. A glancing blow from a minor planet isn't the only thing that can change an obliquity. The tilt of our planet's axis is drifting - ever so slightly - all the time. The poles actually trace out a rather complex dance over time scales ranging from minutes to thousands of centuries. Like a spinning top, our planet also wobbles - though it does so very slowly. Over a period of 26,000 years, the poles trace out a giant circle in the sky. Right now, the north pole points pretty close to the star Polaris. But over time that will change, and in some epochs it will be pointing at nothing at all. This wobble - or precession - doesn't change the amount of obliquity; it simply changes where in space the poles are pointing. The Moon, however, does tug on our planet's axis. In addition to rotation and precession, the Earth experiences something called nutation. This is a slight rocking of the Earth's axis caused by the changing positions of the Moon, the Sun, and all the other bodies in the solar system. With many players involved, the motion from nutation is fairly complex. The main component nods the planet by a couple hundred meters over a nearly 19 year cycle that is tied to how the Moon's orbit drifts around the Earth. Our planet also has to contend with forces much closer to home. Internal motions of magma, deep sea currents, changing ocean salinity, winds, melting ice sheets, and even earthquakes all conspire to constantly change the distribution of mass within the Earth. The planet responds by continuously shifting its spin axis - an effect known as polar motion. This is a bit different than nutation; it actually changes where on Earth the north and south poles are located. Hard as it may be to fathom, these are not fixed locations on the globe. The drift is very small - centimeters per year - but it does add a complex twist to understanding our planets motion in space. The presence of a large moon is believed to help stabilize our obliquity. The tilt does change by a few degrees over many millions of years, but manages to hold steady at around 20-25 degrees. Mars, conversely, appears to be going through a chaotic evolution in its obliquity. Computer simulations of its stability suggest that, over the past few million years, the Red Planet's tilt has oscillated wildly between zero and sixty degrees which may lead to drastic swings in the environment. Many astrobiologists - scientists who study the evolution and origin of life in a cosmic context - argue that our moon may be an essential ingredient for providing a stable environment within which life could thrive. Does this mean that the existence of complex life and advanced civilizations is dependent on the presence of a large satellite? That's hard to say. It is certainly plausible that our closest neighbor in space has been an indispensable partner in the evolution of our species. I'm continually amazed at how a simple concept - like the tilt of a planet - can actually lead down a labyrinthian path of subtleties. Studying Earth's obliquity, and the obliquity of all the other planets and moons, reveals much about the dynamics of our planet, the interplay of our home and neighboring worlds, and even the often times cataclysmic evolution of the solar system. While the subtleties are far removed from our day-to-day lives, our Earth's position in space actually is inseparable from the human experience. The June solstice is just over a month away. Whether you're bundling up for winter, or heading to the beach for summer, remember: the Earth's obliquity is the reason for the seasons! End of podcast: 365 Days of Astronomy ===================== The 365 Days of Astronomy Podcast is produced by the New Media Working Group of the International Year of Astronomy 2009. Audio post-production by Preston Gibson. Bandwidth donated by libsyn.com and wizzard media. Web design by Clockwork Active Media Systems. You may reproduce and distribute this audio for non-commercial purposes. Please consider supporting the podcast with a few dollars (or Euros!). Visit us on the web at 365DaysOfAstronomy.org or email us at info@365DaysOfAstronomy.org. Until tomorrow...goodbye.]]> http://365daysofastronomy.org/2012/05/15/may-15th-astronomy-word-of-the-week-obliquity/feed/ 0 podcast iya 365 Date: May 15, 2012 - Title: Astronomy Word of the Week: Obliquity Podcaster: Dr. Christopher Crockett - Organization: United States Naval Observatory - Links: http://christophercrockett.com http://astrowow.wordpress.com/ - Date: May 15, 2012 Title: Astronomy Word of the Week: Obliquity Podcaster: Dr. Christopher Crockett Organization: United States Naval Observatory Links: http://christophercrockett.com http://astrowow.wordpress.com/ Description: The tilt of our planet is about much more than the seasons. The astronomy word of the week is "obliquity". Bio: Dr. Christopher Crockett is an astronomer at the United States Naval Observatory in Flagstaff, Arizona. His research involves searching for planets around very young stars (“only” a few million years old). It is hoped that the results from this research will help constrain models of planet formation and lead to a better understanding of where, when, and how often planets form. Chris is also passionate about astronomy outreach and education and will talk for hours about the Universe if you let him. Today's Sponsor: "This episode of 365 days of Astronomy" is sponsored by iTelescope.net - Expanding your horizons in astronomy today. The premier on-demand telescope network, at dark sky sites in Spain, New Mexico and Siding Spring, Australia. This episode has also been sponsored by Lake County Astronomical Society: Celebrating 30 years of stellar service to members and the public. Transcript: The planet you're standing on is not very steady. She bobs and wobbles, ducks and weaves, as she makes her annual trek around the Sun. Our home constantly struggles with forces both external and internal; the Sun, the Moon, and the planets tug her back and forth while shifting masses within force her to constantly find new balance. The tilt of our planet's axis - what astronomers call its obliquity - is one measure of this interplanetary tug-of-war. Obliquity measures how far over a planet or moon is tipped relative to its orbit; in the Earth's case, it's about 23 degrees. We feel the obliquity in the changing seasons. In June, the north pole is tipped towards the Sun. The northern hemisphere experiences longer days and more direct sunlight giving us warm summer days. In December, the north pole is tipped away from the Sun and everyone above the equator experiences the bitter chill of winter as the days get shorter and the sunlight reaches us more obliquely. The other planets in our solar system exhibit a wide range of obliquities. Mars, Saturn, and Neptune are all tipped by roughly the same amount as Earth. Mercury and Jupiter have hardly any obliquity at all - which means no seasons for them. Venus' obliquity is 177 degrees; it is almost completely upside down. Put another way, it rotates in the opposite direction from Earth. Were there ever to be a break in Venus' stifling cloud layer, native Venusians would see the Sun rise in the west and set in the east! Uranus is another strange character; his obliquity is 97 degrees. Uranus is lying on his side! This leads to some very strange days and seasons. Each pole of Uranus alternates between being in constant sunlight for 42 years, then perpetual darkness for another 42 years. Only a very thin strip along the equator experiences anything like day/night cycles that we experience - and even then the Sun is frequently sitting very low on the horizon. Astronomers aren't entirely certain how Venus and Uranus came to have such extreme obliquities. A leading hypothesis is that both experienced massive collisions at some point in their distant past, essentially knocking them over. A glancing blow from a minor planet isn't the only thing that can change an obliquity. The tilt of our planet's axis is drifting - ever so slightly - all the time. The poles actually trace out a rather complex dance over time scales ranging from minutes to thousands of centuries. Like a spinning top, our planet also wobbles - though it does so very slowly. Over a period of 26,000 years, the poles trace out a giant circle in the sky. Right now, the north pole points pretty close to the star Polaris. 365 Days of Astronomy no May 14th: Diamond Planet Finder Is A Star http://365daysofastronomy.org/2012/05/14/may-14th-diamond-planet-finder-is-a-star/ http://365daysofastronomy.org/2012/05/14/may-14th-diamond-planet-finder-is-a-star/#comments Mon, 14 May 2012 11:00:46 +0000 kortney.hogan http://365daysofastronomy.org/?p=7683 Date: May 14, 2012 Title: Diamond Planet Finder Is A Star Podcaster: Michael Greenwell Links: http://michaelgreenwell.wordpress.com/ and http://exitstageright.wordpress.com/ Description: Last year, after making an enormously publicized discovery astronomer Matthew Bailes used his moment of fame to defend his scientific colleagues and to try to point us in the direction in which we need to be looking. I think he should be applauded for this and we would do well to listen to what he had to say. Bio: Michael Greenwell has worked, at various times, as a university tutor, a barman, a DJ (not a very good one), an office lackey, supermarket worker, president of a small charity, a researcher, a librarian, a volunteer worker in Nepal during the civil war there, and some other things that were too tedious to mention. He blogs here and also runs the animal extinction site Exit Stage Right. Today's Sponsor: "This episode of 365 days of Astronomy is sponsored by 'The Heliochromologist' " "This episode of 365 days of astronomy was sponsored by iTelescope.net - Expanding your horizons in astronomy today. The premier on-demand telescope network, at dark sky sites in Spain, New Mexico and Siding Spring, Australia." Transcript: At the end of last August, you probably read about the scientists who found a planet that is, in their words “certainly crystalline” or in other words, a large…. well… ok…a VERY large diamond…in fact, it is about 4 times the diameter of the Earth. The planet orbits a pulsar, which they referred to as Beyonce on account of the amount of Bling it was showing off. The story got a lot of coverage but one of the scientists involved, Matthew Bailes, did something a couple of weeks later that was rather brave and just as worthy of note - and I think that he should be applauded for it and that we would do well to listen to what he had to say. Specifically, he wrote an article for an Australian website called “The Conversation” in which he used the opportunity the extensive media coverage this discovery gave him to defend climate scientists and try to draw people’s attention to a problem that is ever worsening ie the fact that while the media are happy to report about weird weather on Jupiter or Saturn for example, they show a certain reluctance to talk about Global Weirding and the problems of Climate change here on planet Earth. I’ll quote to you now a slightly shortened version of what he said…

Following the publication of our finding in the journal Science, our research received amazing attention from the world’s media. I was asked by many journalists about the significance of the discovery. If I were honest, I’d have to concede that, although worthy of publication in Science, in the field of astrophysics it isn’t that significant. And yet the diamond planet has been hugely successful in igniting public curiosity about the universe in which we live. Imagine for a minute that, instead of discovering a diamond planet, we’d made a breakthrough in global temperature projections. Let’s say we studied computer models of the influence of excessive greenhouse gases, verified them through observations, then had them peer-reviewed and published in Science. Instead of sitting back and basking in the glory, I suspect we’d find a lot of commentators, many with no scientific qualifications, pouring scorn on our findings. People on the fringe of science would be quoted as opponents of our work, arguing that it was nothing more than a theory yet to be conclusively proven. Before long our credibility and findings would be under serious question. But luckily we’re not climate scientists. It may come as a big surprise to many, but there is actually no difference between how science works in astronomy and climate change – or any other scientific discipline for that matter. We make observations, run simulations, test and propose hypotheses, and undergo peer review of our findings. Of course we all make mistakes. But eventually the prevailing wisdom of the community triumphs and the field advances. It’s wonderful to be a part of that process. But on occasion those from the fringe of the scientific community will push a position that is simply not credible against the weight of evidence. This occurs within any discipline. But it seems it’s only in the field of climate science that such people are given airtime and column inches to espouse their views. Those who want to ignore what’s happening to Earth feel they need to be able to quote “alternative studies”, regardless of the scientific merit of those studies. In all fields of science, papers are challenged and statistics are debated. If there is any basis to these challenges they stand, but if not they fall by the wayside and the field continues to advance. When big theories fall, it isn’t because of business or political pressures – it’s because of the scientific process. Sadly, the same media commentators who celebrate diamond planets without question are all too quick to dismiss the latest peer-reviewed evidence that suggests man-made activities are responsible for changes in concentrations of CO2 in our atmosphere. The scientific method is universal. If we selectively ignore it in certain disciplines, we do so at our peril.

"Should the free precession be accepted as the correct explanation of the phenomena, it will give an important tool to study white dwarf equations of state. The theory of compact objects predicts certain relations between the spin and precession periods, and our finding provides a good test for the theory and establishes a qualitative model to be explored both theoretically and observationally. Detection of precession can become a powerful tool in searching for the internal properties of compact stars, which would be otherwise inaccessible for us. Combined with other methods to estimate masses and density of the WDs in CVs, the precession period will help to refine these values, which in turn, allows for testing and proving the theory for the precession of compact stars and may allow for further advances in our knowledge of the structure of WDs and the influence of accretion on them."

Some interesting things were also observed in the quiescent state prompting additional scrutiny during this year's season of the longer term behaviour of the system when at quiescence. It has been great to be a part of the wonderful science research that is still ongoing. Its all part of the great science you can do as a part of any number of citizen science initiatives. The AAVSO and Variable Stars South have many and varied research projects just like this one where you can play a significant part in gathering the data and working with professional astronomers. It was great working with such professional people ably lead by Vitaly and George Sjoberg. Participation in campaigns like this is a great way to get to know other astronomers, and build your credibility as a capable amateur astronomer. End of podcast: 365 Days of Astronomy ===================== The 365 Days of Astronomy Podcast is produced by the Astrosphere New Media Association. Audio post-production by Preston Gibson. Bandwidth donated by libsyn.com and wizzard media. Web design by Clockwork Active Media Systems. You may reproduce and distribute this audio for non-commercial purposes. Please consider supporting the podcast with a few dollars (or Euros!). Visit us on the web at 365DaysOfAstronomy.org or email us at info@365DaysOfAstronomy.org. Until tomorrow...goodbye.]]> http://365daysofastronomy.org/2012/05/10/may-10th-twinkle-twinkle-little-star-how-i-wonder-fs-aur/feed/ 0 podcast iya 365 Date: May 10, 2012 - Title: Twinkle Twinkle little star ...... How I wonder FS Aur? - Podcaster: Peter Lake - Organization: AARTScope Blog - Links: http://aartscope.blogspot.com http://vitaly.neustroev.net/research/observing-campaigns/ http://www. Date: May 10, 2012 Title: Twinkle Twinkle little star ...... How I wonder FS Aur? Podcaster: Peter Lake Organization: AARTScope Blog Links: http://aartscope.blogspot.com http://vitaly.neustroev.net/research/observing-campaigns/ http://www.twitter.com/fs_Aur http://www.aavso.org Description: FS Aur is one of the most strangest and erratic variable Stars. Peter Lake reports on the data collected as part of the broader work with Dr Vitaly Neustroev of the Oulu University Finland and discusses the past two seasons of observations. Peter Lake is an Amateur Astronomer from Melbourne Australia and regularly discusses how people can be involved in citizen science and observation programs. Bio: Peter Lake is an amateur Astronomer from Melbourne, Australia, a member of Variable Stars South and the AAVSO and he owns and operates a 0.5m Planewave CDK Telescope at New Mexico skies, which is affiliated to iTelescope.net. Peter has been a participant in citizen science and recovered asteroid 2000 EV70 during the Spacewatch FMO program. More recently Peter has been actively involved in the study of cataclysmic variable star FS Aur, and followup exoplanet observations on Kepler targets of interest. Sponsor: "This episode of 365 days of astronomy is sponsored with thanks to all non-US contributors for showing us that the night sky is something we can all share." "Additional sponsorship for this episode of 365 days of astronomy was provided by iTelescope.net - Expanding your horizons in astronomy today. The premier on-demand telescope network, at dark sky sites in Spain, New Mexico and Siding Spring, Australia." Transcript: Like duck hunting, Variable Stars have their "Seasons" also. A season being where the variable star in question is in the optimal position for "shooting with CCDs" ie observable for most of the night, during this time ideally it can be visible for as many as 6-7 hours per night. FS Aur is a Cataclysmic Variable is now low in the west at sunset at the close of an intensive second season. So I though it would be good to review these past two seasons, before once again, it comes around for observations in the next northern winter. FS Aur is one of the strangest and complex objects in the extensive variable star family. It is thought to be a magnetic white dwarf and red giant binary Star with a third object acting on it in a circumbinary orbit. (Tovmassian et al., 2010) Back in 2010 there was a sporadic and incomplete light curve and astronomers wanted answers. When they want answers they often leverage the collective effort of the American Association of Variable Star Observers (AAVSO), to muscle up some more observations and data. FS Aur has a number of photometric and spectroscopic cycles going on. On top of this it goes into outburst about every 12-15 days. The outburst duration is so short (2-3 days) it has been regularly missed in the past - so in the 2010/11 season Dr Neustroev rallied a special effort. For the first time, members of the AAVSO mapped the entire outburst cycle, a good number of times. Dr Vitaly Neustroev is the University Researcher (Yliopistotutkija) at the University of Oulu, Finland and he is a key researcher on FS Aur, working hard to better understand its erratic behaviour. Visit the observing campaign page here, and also follow on (Twitter). I like following Cataclysmic Variables, after catching Simostronomy fever, and I have been a regular on FS Aur since Dr Neustroev's call to action. During the campaign FS Aur has been dancing away with a little periodic wobble at about 15.9 with the odd subtle change in brightness, then it goes really dull to 16.2 then literally within 24-36 hours it pops up to magnitude about Mag 14. As an amateur astronomer I am always careful to point out that I'm not qualified to say how or why, but I can tell you when, where and how bright! So what is going on with FS Aur - Dr Neustroev describes it this way: 365 Days of Astronomy no May 9th: Astronomy Word of the Week: Nova http://365daysofastronomy.org/2012/05/09/may-9th-astronomy-word-of-the-week-nova/ http://365daysofastronomy.org/2012/05/09/may-9th-astronomy-word-of-the-week-nova/#comments Wed, 09 May 2012 11:00:09 +0000 kortney.hogan http://365daysofastronomy.org/?p=7650 Date: May 9, 2012 Title: Astronomy Word of the Week: Nova Podcaster: Dr. Christopher Crockett Organization: United States Naval Observatory Links: http://christophercrockett.com http://astrowow.wordpress.com/ Description: Why do once invisible stars suddenly flare up and then slowly fade from view? The astronomy word of the week is "nova". Bio: Dr. Christopher Crockett is an astronomer at the United States Naval Observatory in Flagstaff, Arizona. His research involves searching for planets around very young stars (“only” a few million years old). It is hoped that the results from this research will help constrain models of planet formation and lead to a better understanding of where, when, and how often planets form. Chris is also passionate about astronomy outreach and education and will talk for hours about the Universe if you let him. Sponsors: Sponsorship for this episode of "365 days of Astronomy" is donated anonymously and dedicated to the men and women of NASA who strive to turn science fiction into science reality. Additional sponsorship for this episode has been provided by iTelescope.net - Expanding your horizons in astronomy today. The premier on-demand telescope network, at dark sky sites in Spain, New Mexico and Siding Spring, Australia. Transcript: In 1572, Danish astronomer Tycho Brahe, along with observers around the world, noticed a new star in the constellation Casseiopeia. Rivaling Venus as the brightest object in the night sky after the Moon, the unexpected guest remained visible for nearly two years before fading from view. The appearance of a new star was nothing short of revolutionary; astronomers long agreed that the celestial sphere was unchanging. A transient star challenged this assumption and suggested that the heavens were perhaps more dynamic than originally thought. The celestial intruder came to be known as a "nova" - after Tycho Brahe's extensive manuscript on the phenomenon - where he referred to the object simply by the latin term for a new star: "stella nova". While no one could have known it at the time, the new star was actually not new at all but rather a very old star experiencing a cataclysmic event. Most of the stars in the sky are not singular, like our Sun, but rather members of binary star systems - two stars locked in orbit around one another. Of this pair, one star is often more massive than its companion and therefore burns through its nuclear fuel at a faster rate. The heavier star reaches the end of its life before its sibling. When it does, the star inflates to become a red giant and sheds its outer layers into space leaving behind the hot, dense stellar core. The naked core, known as a "white dwarf", continues to orbit its stellar neighbor while taking the next few billion years to passively cool from a white-hot 100,000 degrees. In the case of close binary pairs, the white dwarf can actually siphon matter off of its companion. The intermingled gravitational fields of the two stars builds a bridge of predominately hydrogen gas spanning the distance between them. Gas from the still active star flows through this gravitational funnel and spills on to the surface of the white dwarf. The mass of the white dwarf controls the rate of mass accretion; if the rate is high enough, then something quite spectacular can happen. White dwarfs are an example of a rather exotic type of matter that physicists call "degenerate". Most gasses expand when you heat them up: the increasing temperature causes the molecules to zip around faster which in turn increases the gas pressure. At extreme densities - like those seen in the cores of stars - the gas behaves rather peculiarly. The pressure is no longer a slave to temperature: turn up the heat and the gas does not expand. This counterintuitive behavior is crucial to what happens next on the white dwarf's surface. As hydrogen from the donor star comes crashing down, the crushing force of gravity compresses it into a degenerate state and the intense radiation heats the gas to many millions of degrees. But having now obtained the properties of a degenerate gas, the newly acquired hydrogen shell doesn't expand in response to the rapid heating, but holds its pressure steady. And now things get interesting. At temperatures exceeding 16 million degrees Celsius, conditions on the surface mimic those deep in the cores of stars and a thermonuclear explosion is the result. Hydrogen is rapidly fused into helium and the resulting release of energy blows the outer hydrogen shell off the surface of the white dwarf at speeds exceeding ten million kilometers per hour. In mere days, the white dwarf can increase its brightness by 100,000 times. It can then take months - or in some cases years - for the star to slowly fade from view. Our Milky Way Galaxy experiences several dozen novae each year, only about ten of which are visible from Earth. A few are even visible to the naked eye. The most recent nova to be seen without the aid of binoculars or telescopes did so in the constellation Scorpius, reaching its peak brightness on February 17, 2007. Even more rare are what astronomers call "recurrent nova". Once the white dwarf has blown the hydrogen shell into space, the gas can slowly start building up again. These are novae that flare up repeatedly, sometimes once a year, sometimes once every couple of decades. In our whole galaxy, only ten novae are known to be recurrent. In the centuries since the new star of 1572, astronomers have come to realize that the event which gave novae their name was not what we know now as a nova. Up until early in the 20th century, a nova referred to any rapid brightening of a star. But there are many reasons stars suddenly flare into view. What Tycho saw was actually something far more powerful - a type of, aptly named, supernova. The supernova of 1572 was not the result of a flash of hydrogen burning on a white dwarf shell, but rather was caused by the complete detonation of a white dwarf. By stealing gas from a nearby companion slowly enough, the progenitor of the supernova delayed a nova flash while gradually increasing its temperature and pressure and eventually igniting hydrogen fusion throughout the interior of the once dead stellar core. With out the counterbalancing force of the rest of the star to throttle these reactions, the now violently active core obliterated itself in one of the most powerful explosions the Universe can produce. The event of 1572 ushered in a new era of astronomy, one in which the constancy of the celestial sphere could no longer be assumed. Novae - and their more powerful supernovae cousins - are constant reminders that we, in fact, live in a highly dynamic and energetic Universe. End of podcast: 365 Days of Astronomy ===================== The 365 Days of Astronomy Podcast is produced by the Astrosphere New Media Association. Audio post-production by Preston Gibson. Bandwidth donated by libsyn.com and wizzard media. Web design by Clockwork Active Media Systems. You may reproduce and distribute this audio for non-commercial purposes. Please consider supporting the podcast with a few dollars (or Euros!). Visit us on the web at 365DaysOfAstronomy.org or email us at info@365DaysOfAstronomy.org. Until tomorrow...goodbye.]]> http://365daysofastronomy.org/2012/05/09/may-9th-astronomy-word-of-the-week-nova/feed/ 0 podcast iya 365 Date: May 9, 2012 - Title: Astronomy Word of the Week: Nova - Podcaster: Dr. Christopher Crockett - Organization: United States Naval Observatory - Links: http://christophercrockett.com http://astrowow.wordpress.com/ - Date: May 9, 2012 Title: Astronomy Word of the Week: Nova Podcaster: Dr. Christopher Crockett Organization: United States Naval Observatory Links: http://christophercrockett.com http://astrowow.wordpress.com/ Description: Why do once invisible stars suddenly flare up and then slowly fade from view? The astronomy word of the week is "nova". Bio: Dr. Christopher Crockett is an astronomer at the United States Naval Observatory in Flagstaff, Arizona. His research involves searching for planets around very young stars (“only” a few million years old). It is hoped that the results from this research will help constrain models of planet formation and lead to a better understanding of where, when, and how often planets form. Chris is also passionate about astronomy outreach and education and will talk for hours about the Universe if you let him. Sponsors: Sponsorship for this episode of "365 days of Astronomy" is donated anonymously and dedicated to the men and women of NASA who strive to turn science fiction into science reality. Additional sponsorship for this episode has been provided by iTelescope.net - Expanding your horizons in astronomy today. The premier on-demand telescope network, at dark sky sites in Spain, New Mexico and Siding Spring, Australia. Transcript: In 1572, Danish astronomer Tycho Brahe, along with observers around the world, noticed a new star in the constellation Casseiopeia. Rivaling Venus as the brightest object in the night sky after the Moon, the unexpected guest remained visible for nearly two years before fading from view. The appearance of a new star was nothing short of revolutionary; astronomers long agreed that the celestial sphere was unchanging. A transient star challenged this assumption and suggested that the heavens were perhaps more dynamic than originally thought. The celestial intruder came to be known as a "nova" - after Tycho Brahe's extensive manuscript on the phenomenon - where he referred to the object simply by the latin term for a new star: "stella nova". While no one could have known it at the time, the new star was actually not new at all but rather a very old star experiencing a cataclysmic event. Most of the stars in the sky are not singular, like our Sun, but rather members of binary star systems - two stars locked in orbit around one another. Of this pair, one star is often more massive than its companion and therefore burns through its nuclear fuel at a faster rate. The heavier star reaches the end of its life before its sibling. When it does, the star inflates to become a red giant and sheds its outer layers into space leaving behind the hot, dense stellar core. The naked core, known as a "white dwarf", continues to orbit its stellar neighbor while taking the next few billion years to passively cool from a white-hot 100,000 degrees. In the case of close binary pairs, the white dwarf can actually siphon matter off of its companion. The intermingled gravitational fields of the two stars builds a bridge of predominately hydrogen gas spanning the distance between them. Gas from the still active star flows through this gravitational funnel and spills on to the surface of the white dwarf. The mass of the white dwarf controls the rate of mass accretion; if the rate is high enough, then something quite spectacular can happen. White dwarfs are an example of a rather exotic type of matter that physicists call "degenerate". Most gasses expand when you heat them up: the increasing temperature causes the molecules to zip around faster which in turn increases the gas pressure. At extreme densities - like those seen in the cores of stars - the gas behaves rather peculiarly. The pressure is no longer a slave to temperature: turn up the heat and the gas does not expand. This counterintuitive behavior is crucial to what happens next on the white dwarf's surface. As hydrogen from the donor star comes crashing down, 365 Days of Astronomy no May 8th: What is Black http://365daysofastronomy.org/2012/05/08/may-8th-what-is-black/ http://365daysofastronomy.org/2012/05/08/may-8th-what-is-black/#comments Tue, 08 May 2012 11:00:41 +0000 kortney.hogan http://365daysofastronomy.org/?p=7646 Date: May 8, 2012 Title: What is Black Podcaster: Rob Sparks & Dr. Steven Pompea Organization: NOAO Links: www.noao.edu Description: Most people think of black as a color, but black is really the absence of light. Truly black surfaces reflect almost none of the light that falls on them. In this podcast, Dr. Stephen Pompea discusses black surface, how they are produced and why they are important in astronomy and other sciences. Bio: Rob Sparks is a science education specialist in the EPO group at NOAO and works on the Galileoscope project (www.galileoscope.org), providing design, dissemination and professional development. He also pens a great blog at halfastro.wordpress.com. Dr. Stephen Pompea did his undergraduate work in physics, space physics, and astronomy at Rice University, his Master’s work in physics teaching at Colorado State University, and his Ph.D. in astronomy at the University of Arizona. He is currently the manager of the Education and Public Outreach Group at the National Optical Astronomy Observatory. Sponsor: This episode of the 365 Days of Astronomy podcast is sponsored by the National Optical Astronomy Observatory. NOAO is a US national research and development center for ground-based nighttime astronomy. We provide astronomers access to world-class observing facilities on a peer-reviewed basis. Our mission is to engage in programs to develop the next generation of telescopes, instruments, and software tools necessary to enable exploration and investigation through the observable Universe. For information on observing proposals or our public programs, please visit www.noao.edu for more information. "This episode has also been sponsored by the Lake County Astronomical Society: Celebrating 30 years of stellar service to members and the public." Transcript: *** Transcript coming soon. *** End of podcast: 365 Days of Astronomy ===================== The 365 Days of Astronomy Podcast is produced by the Astrosphere New Media Association. Audio post-production by Preston Gibson. Bandwidth donated by libsyn.com and wizzard media. Web design by Clockwork Active Media Systems. You may reproduce and distribute this audio for non-commercial purposes. Please consider supporting the podcast with a few dollars (or Euros!). Visit us on the web at 365DaysOfAstronomy.org or email us at info@365DaysOfAstronomy.org. Until tomorrow...goodbye.]]> http://365daysofastronomy.org/2012/05/08/may-8th-what-is-black/feed/ 0 podcast iya 365 Date: May 8, 2012 - Title: What is Black - Podcaster: Rob Sparks & Dr. Steven Pompea - Organization: NOAO - Links: www.noao.edu - Description: Most people think of black as a color, but black is really the absence of light. Date: May 8, 2012 Title: What is Black Podcaster: Rob Sparks & Dr. Steven Pompea Organization: NOAO Links: www.noao.edu Description: Most people think of black as a color, but black is really the absence of light. Truly black surfaces reflect almost none of the light that falls on them. In this podcast, Dr. Stephen Pompea discusses black surface, how they are produced and why they are important in astronomy and other sciences. Bio: Rob Sparks is a science education specialist in the EPO group at NOAO and works on the Galileoscope project (www.galileoscope.org), providing design, dissemination and professional development. He also pens a great blog at halfastro.wordpress.com. Dr. Stephen Pompea did his undergraduate work in physics, space physics, and astronomy at Rice University, his Master’s work in physics teaching at Colorado State University, and his Ph.D. in astronomy at the University of Arizona. He is currently the manager of the Education and Public Outreach Group at the National Optical Astronomy Observatory. Sponsor: This episode of the 365 Days of Astronomy podcast is sponsored by the National Optical Astronomy Observatory. NOAO is a US national research and development center for ground-based nighttime astronomy. We provide astronomers access to world-class observing facilities on a peer-reviewed basis. Our mission is to engage in programs to develop the next generation of telescopes, instruments, and software tools necessary to enable exploration and investigation through the observable Universe. For information on observing proposals or our public programs, please visit www.noao.edu for more information. "This episode has also been sponsored by the Lake County Astronomical Society: Celebrating 30 years of stellar service to members and the public." Transcript: *** Transcript coming soon. *** End of podcast: 365 Days of Astronomy ===================== The 365 Days of Astronomy Podcast is produced by the Astrosphere New Media Association. Audio post-production by Preston Gibson. Bandwidth donated by libsyn.com and wizzard media. Web design by Clockwork Active Media Systems. You may reproduce and distribute this audio for non-commercial purposes. Please consider supporting the podcast with a few dollars (or Euros!). Visit us on the web at 365DaysOfAstronomy.org or email us at info@365DaysOfAstronomy.org. Until tomorrow...goodbye. 365 Days of Astronomy no May 7th: The Late Heavy Bombardment — an Extended Version? http://365daysofastronomy.org/wp-content/plugins/powerpress/rss_default.jpg http://365daysofastronomy.org 365 Days of Astronomy http://365daysofastronomy.org An astronomy podcast every day, all year Wed, 16 May 2012 11:00:41 +0000 en hourly 1 http://wordpress.org/?v=3.1 An astronomy podcast every day, all year 365 Days of Astronomy no An astronomy podcast every day, all year 365 Days of Astronomy http://365daysofastronomy.org/wp-content/plugins/powerpress/rss_default.jpg http://365daysofastronomy.org May 16th: GPS http://365daysofastronomy.org/2012/05/16/may-16th-gps/ http://365daysofastronomy.org/2012/05/16/may-16th-gps/#comments Wed, 16 May 2012 11:00:41 +0000 kortney.hogan http://365daysofastronomy.org/?p=7689 Date: May 16, 2012 Title: GPS Podcaster: Steve Nerlich Organization: Cheap Astronomy Links: www.cheapastro.com Description: Cheap Astronomy once again demonstrates that pretty much everything in life has a connection to astronomy. Bio: Cheap Astronomy offers an educational website because in space no-one can hear you podcast. Today's Sponsor: "This episode of 365 days of Astronomy" is sponsored by the Lake County Astronomical Society: Celebrating 30 years of stellar service to members and the public." Additional sponsorship for this episode has also been provided by iTelescope.net - Expanding your horizons in astronomy today. The premier on-demand telescope network, at dark sky sites in Spain, New Mexico and Siding Spring, Australia. Transcript: Hi this is Steve Nerlich from Cheap Astronomy www.cheapastro.com and this is GPS OK – If you don’t have one, you know someone who does, so let’s skip the introductions and get straight down to the astronomy. A standard GPS configuration is a constellation of 24 GPS satellites. The satellites are all at an altitude of 20,200 km with an orbital period of 11 hours and 58 minutes – which means they do exactly 2 orbits for each time the Earth spins once on its axis. Four satellites each follow six orbital planes separated by 60 degrees which surround the Earth in an (airquotes) ‘birdcage’ of criss-crossing orbits. There a link to the relevant Wikipedia article from the Cheap Astronomy podcast page which has a nice animation of a GPS satellite constellation. At last count, there were actually 31 actively transmitting GPS satellites – with these extra number increasing location accuracy and redundancy. There’s been some recent media regarding a growing risk of dropping below the minimum 24 active satellites required to make GPS work effectively, but it remains to be seen if this risk will be realised in the face of the increasing economic importance of maintaining a working GPS system. A GPS satellite broadcasts a signal indicating where it is and the time the signal was broadcast – your receiver then determines, from the time it receives that signal, the distance travelled by the signal, knowing that, being a radio transmission, the signal travels at the speed of light. By making just four calculations from four satellites in the sky, your GPS receiver can then establish its position with respect to latitude, longitude and altitude. It’s all about the conjunction of spheres. Imagine one satellite broadcasting a radio signal. If you pick up that signal and determine it’s a 100 km away, all you really know is that you are somewhere on a surface of a sphere with a 100 km radius that has the satellite at its centre. If there’s two such satellites then you’ll know you are somewhere on the circumference of a circle representing the plane where the two spheres of radio broadcast overlap. Introduce a third satellite and you can narrow down your location to just two points in space which are the points where two differently orientated circle circumferences intersect. Potentially this may be enough to roughly determine your position since you can anticipate you will be on the one of those two points corresponding to the surface of the Earth. But for strictest accuracy – including accuracy in determining your altitude above sea level, the signal from a fourth satellite is required. And that is the idea of the constellation of GPS satellites. Keeping 24 satellites moving in the same orbit, tracing a birdcage of divergent paths around the globe ensures there will always be four satellites in the sky wherever you happen to be on Earth. Now when I say GPS satellites just have to broadcast where they are – actually knowing where they are is a whole separate operation, While the orbital period is predictable, knowing at what point they are on that orbit requires some very accurate time keeping – for which reason each satellite has an atomic clock. Nonetheless, even this isn’t enough, as the orbital paths of the satellites are subject to slight shifting due to the gravitational influence of the Sun and the Moon. To keep track of these changes the satellites are monitored from a fixed, known location on the Earth’s surface – a function currently managed by the 50th Space Wing of the US Airforce Space Command – seriously. Now, given that your GPS receiver is working out its distance from each of four satellites based solely on the time lag of a signal moving at the speed of light from a satellite just over 20,000 kilometres away – there is considerable potential for a margin of error that could see you driving over the embankment into a river when that sexy voice says ‘turn left now’. There are a range of methods to deal with various sources of error. Firstly your GPS receiver carries an electronic almanac of which satellite should be where since confusion can arise when the satellite radio signals get reflected off surroundings, such as tall buildings. This electronic almanac is constructed from calibration data received from the GPS satellites, although these data are generally relayed from a ground-based source – such as Airforce Space Command. The almanac helps your receiver distinguish between garbage signals and genuine GPS signals. The receiver also receives time checks from the satellites since, most GPS receivers determine time from a cheap (not that there’s anything wrong with that) quartz clock rather than the ultra-accurate atomic clocks of the satellites. Clock error is probably the biggest potential source of GPS error, which is why, even though you could almost get away with determining your position from just 3 satellites, it is the fourth reading (which we might call quadrangulation) that ensures the poorer accuracy of the GPS receiver’s clock is effectively accounted for. Interestingly, there’s also relativistic effects to account for, since the satellites move in a weaker gravity field (meaning by general relativity their clocks run faster), and they also move at speed relative to the surface of the Earth (meaning by special relativity their clocks run slower). It turns out that the nett effect is that the satellites’ clocks run about 38 microseconds per day faster than they would at the Earth’s surface. To account for this, the clocks are actually set to run at a slightly lower rate, to keep pace with clocks running on the Earth’s surface. In the world of atomic clocks, various time keeping callibrations are also required to account for changes in the rotation of the Earth – which is influenced by the tidal drag of the Moon , the inertia of the Earth’s molten interior and even the melting of glaciers. Overall, the Earth’s rotation is slowing, leading to a lengthening of a solar day. Consequently a leap second must be introduced to atomic timepieces which measure Universal Coordinated Time (known as UTC – because of the French). In fact, a leap second is required to be added to UTC every 18 months or so because each year (on average) the length of a solar day increases by about 0.002 seconds. The atomic clocks of GPS satellites were aligned to UTC in 1980 – but as of 2009, these atomic clocks in orbit now vary by 19 seconds and to keep it simple we just say they are running at GPS time. Various under-the-hood adjustments are made along the way so that your GPS receiver can tell you the local time wherever you happen to be – as well as telling you where you are of course to within… well, within 10 metres is the general benchmark, although this takes a few minutes to establish after the unit is turned on and the accuracy will degrade with tall trees or buildings around. So, you know, it’s a guide – not an absolute – it’s still a good idea to keep one eye on the road. Thanks for listening. This is Steve Nerlich from Cheap Astronomy, www.cheapastro.com. Cheap Astronomy offers an educational website where you can’t put a price on space. No ads, no profit, just good science. Bye. End of podcast: 365 Days of Astronomy ===================== The 365 Days of Astronomy Podcast is produced by the New Media Working Group of the International Year of Astronomy 2009. Audio post-production by Preston Gibson. Bandwidth donated by libsyn.com and wizzard media. Web design by Clockwork Active Media Systems. You may reproduce and distribute this audio for non-commercial purposes. Please consider supporting the podcast with a few dollars (or Euros!). Visit us on the web at 365DaysOfAstronomy.org or email us at info@365DaysOfAstronomy.org. Until tomorrow...goodbye.]]> http://365daysofastronomy.org/2012/05/16/may-16th-gps/feed/ 0 podcast iya 365 Date: May 16, 2012 - Title: GPS Podcaster: Steve Nerlich - Organization: Cheap Astronomy - Links: www.cheapastro.com - Description: Cheap Astronomy once again demonstrates that pretty much everything in life has a connection to astronomy. - Date: May 16, 2012 Title: GPS Podcaster: Steve Nerlich Organization: Cheap Astronomy Links: www.cheapastro.com Description: Cheap Astronomy once again demonstrates that pretty much everything in life has a connection to astronomy. B... 365 Days of Astronomy no May 15th: Astronomy Word of the Week: Obliquity http://365daysofastronomy.org/2012/05/15/may-15th-astronomy-word-of-the-week-obliquity/ http://365daysofastronomy.org/2012/05/15/may-15th-astronomy-word-of-the-week-obliquity/#comments Tue, 15 May 2012 11:00:14 +0000 kortney.hogan http://365daysofastronomy.org/?p=7687 Date: May 15, 2012 Title: Astronomy Word of the Week: Obliquity Podcaster: Dr. Christopher Crockett Organization: United States Naval Observatory Links: http://christophercrockett.com http://astrowow.wordpress.com/ Description: The tilt of our planet is about much more than the seasons. The astronomy word of the week is "obliquity". Bio: Dr. Christopher Crockett is an astronomer at the United States Naval Observatory in Flagstaff, Arizona. His research involves searching for planets around very young stars (“only” a few million years old). It is hoped that the results from this research will help constrain models of planet formation and lead to a better understanding of where, when, and how often planets form. Chris is also passionate about astronomy outreach and education and will talk for hours about the Universe if you let him. Today's Sponsor: "This episode of 365 days of Astronomy" is sponsored by iTelescope.net - Expanding your horizons in astronomy today. The premier on-demand telescope network, at dark sky sites in Spain, New Mexico and Siding Spring, Australia. This episode has also been sponsored by Lake County Astronomical Society: Celebrating 30 years of stellar service to members and the public. Transcript: The planet you're standing on is not very steady. She bobs and wobbles, ducks and weaves, as she makes her annual trek around the Sun. Our home constantly struggles with forces both external and internal; the Sun, the Moon, and the planets tug her back and forth while shifting masses within force her to constantly find new balance. The tilt of our planet's axis - what astronomers call its obliquity - is one measure of this interplanetary tug-of-war. Obliquity measures how far over a planet or moon is tipped relative to its orbit; in the Earth's case, it's about 23 degrees. We feel the obliquity in the changing seasons. In June, the north pole is tipped towards the Sun. The northern hemisphere experiences longer days and more direct sunlight giving us warm summer days. In December, the north pole is tipped away from the Sun and everyone above the equator experiences the bitter chill of winter as the days get shorter and the sunlight reaches us more obliquely. The other planets in our solar system exhibit a wide range of obliquities. Mars, Saturn, and Neptune are all tipped by roughly the same amount as Earth. Mercury and Jupiter have hardly any obliquity at all - which means no seasons for them. Venus' obliquity is 177 degrees; it is almost completely upside down. Put another way, it rotates in the opposite direction from Earth. Were there ever to be a break in Venus' stifling cloud layer, native Venusians would see the Sun rise in the west and set in the east! Uranus is another strange character; his obliquity is 97 degrees. Uranus is lying on his side! This leads to some very strange days and seasons. Each pole of Uranus alternates between being in constant sunlight for 42 years, then perpetual darkness for another 42 years. Only a very thin strip along the equator experiences anything like day/night cycles that we experience - and even then the Sun is frequently sitting very low on the horizon. Astronomers aren't entirely certain how Venus and Uranus came to have such extreme obliquities. A leading hypothesis is that both experienced massive collisions at some point in their distant past, essentially knocking them over. A glancing blow from a minor planet isn't the only thing that can change an obliquity. The tilt of our planet's axis is drifting - ever so slightly - all the time. The poles actually trace out a rather complex dance over time scales ranging from minutes to thousands of centuries. Like a spinning top, our planet also wobbles - though it does so very slowly. Over a period of 26,000 years, the poles trace out a giant circle in the sky. Right now, the north pole points pretty close to the star Polaris. But over time that will change, and in some epochs it will be pointing at nothing at all. This wobble - or precession - doesn't change the amount of obliquity; it simply changes where in space the poles are pointing. The Moon, however, does tug on our planet's axis. In addition to rotation and precession, the Earth experiences something called nutation. This is a slight rocking of the Earth's axis caused by the changing positions of the Moon, the Sun, and all the other bodies in the solar system. With many players involved, the motion from nutation is fairly complex. The main component nods the planet by a couple hundred meters over a nearly 19 year cycle that is tied to how the Moon's orbit drifts around the Earth. Our planet also has to contend with forces much closer to home. Internal motions of magma, deep sea currents, changing ocean salinity, winds, melting ice sheets, and even earthquakes all conspire to constantly change the distribution of mass within the Earth. The planet responds by continuously shifting its spin axis - an effect known as polar motion. This is a bit different than nutation; it actually changes where on Earth the north and south poles are located. Hard as it may be to fathom, these are not fixed locations on the globe. The drift is very small - centimeters per year - but it does add a complex twist to understanding our planets motion in space. The presence of a large moon is believed to help stabilize our obliquity. The tilt does change by a few degrees over many millions of years, but manages to hold steady at around 20-25 degrees. Mars, conversely, appears to be going through a chaotic evolution in its obliquity. Computer simulations of its stability suggest that, over the past few million years, the Red Planet's tilt has oscillated wildly between zero and sixty degrees which may lead to drastic swings in the environment. Many astrobiologists - scientists who study the evolution and origin of life in a cosmic context - argue that our moon may be an essential ingredient for providing a stable environment within which life could thrive. Does this mean that the existence of complex life and advanced civilizations is dependent on the presence of a large satellite? That's hard to say. It is certainly plausible that our closest neighbor in space has been an indispensable partner in the evolution of our species. I'm continually amazed at how a simple concept - like the tilt of a planet - can actually lead down a labyrinthian path of subtleties. Studying Earth's obliquity, and the obliquity of all the other planets and moons, reveals much about the dynamics of our planet, the interplay of our home and neighboring worlds, and even the often times cataclysmic evolution of the solar system. While the subtleties are far removed from our day-to-day lives, our Earth's position in space actually is inseparable from the human experience. The June solstice is just over a month away. Whether you're bundling up for winter, or heading to the beach for summer, remember: the Earth's obliquity is the reason for the seasons! End of podcast: 365 Days of Astronomy ===================== The 365 Days of Astronomy Podcast is produced by the New Media Working Group of the International Year of Astronomy 2009. Audio post-production by Preston Gibson. Bandwidth donated by libsyn.com and wizzard media. Web design by Clockwork Active Media Systems. You may reproduce and distribute this audio for non-commercial purposes. Please consider supporting the podcast with a few dollars (or Euros!). Visit us on the web at 365DaysOfAstronomy.org or email us at info@365DaysOfAstronomy.org. Until tomorrow...goodbye.]]> http://365daysofastronomy.org/2012/05/15/may-15th-astronomy-word-of-the-week-obliquity/feed/ 0 podcast iya 365 Date: May 15, 2012 - Title: Astronomy Word of the Week: Obliquity Podcaster: Dr. Christopher Crockett - Organization: United States Naval Observatory - Links: http://christophercrockett.com http://astrowow.wordpress.com/ - Date: May 15, 2012 Title: Astronomy Word of the Week: Obliquity Podcaster: Dr. Christopher Crockett Organization: United States Naval Observatory Links: http://christophercrockett.com http://astrowow.wordpress.com/ Description: The tilt of our planet is about much more than the seasons. The astronomy word of the week is "obliquity". Bio: Dr. Christopher Crockett is an astronomer at the United States Naval Observatory in Flagstaff, Arizona. His research involves searching for planets around very young stars (“only” a few million years old). It is hoped that the results from this research will help constrain models of planet formation and lead to a better understanding of where, when, and how often planets form. Chris is also passionate about astronomy outreach and education and will talk for hours about the Universe if you let him. Today's Sponsor: "This episode of 365 days of Astronomy" is sponsored by iTelescope.net - Expanding your horizons in astronomy today. The premier on-demand telescope network, at dark sky sites in Spain, New Mexico and Siding Spring, Australia. This episode has also been sponsored by Lake County Astronomical Society: Celebrating 30 years of stellar service to members and the public. Transcript: The planet you're standing on is not very steady. She bobs and wobbles, ducks and weaves, as she makes her annual trek around the Sun. Our home constantly struggles with forces both external and internal; the Sun, the Moon, and the planets tug her back and forth while shifting masses within force her to constantly find new balance. The tilt of our planet's axis - what astronomers call its obliquity - is one measure of this interplanetary tug-of-war. Obliquity measures how far over a planet or moon is tipped relative to its orbit; in the Earth's case, it's about 23 degrees. We feel the obliquity in the changing seasons. In June, the north pole is tipped towards the Sun. The northern hemisphere experiences longer days and more direct sunlight giving us warm summer days. In December, the north pole is tipped away from the Sun and everyone above the equator experiences the bitter chill of winter as the days get shorter and the sunlight reaches us more obliquely. The other planets in our solar system exhibit a wide range of obliquities. Mars, Saturn, and Neptune are all tipped by roughly the same amount as Earth. Mercury and Jupiter have hardly any obliquity at all - which means no seasons for them. Venus' obliquity is 177 degrees; it is almost completely upside down. Put another way, it rotates in the opposite direction from Earth. Were there ever to be a break in Venus' stifling cloud layer, native Venusians would see the Sun rise in the west and set in the east! Uranus is another strange character; his obliquity is 97 degrees. Uranus is lying on his side! This leads to some very strange days and seasons. Each pole of Uranus alternates between being in constant sunlight for 42 years, then perpetual darkness for another 42 years. Only a very thin strip along the equator experiences anything like day/night cycles that we experience - and even then the Sun is frequently sitting very low on the horizon. Astronomers aren't entirely certain how Venus and Uranus came to have such extreme obliquities. A leading hypothesis is that both experienced massive collisions at some point in their distant past, essentially knocking them over. A glancing blow from a minor planet isn't the only thing that can change an obliquity. The tilt of our planet's axis is drifting - ever so slightly - all the time. The poles actually trace out a rather complex dance over time scales ranging from minutes to thousands of centuries. Like a spinning top, our planet also wobbles - though it does so very slowly. Over a period of 26,000 years, the poles trace out a giant circle in the sky. Right now, the north pole points pretty close to the star Polaris. 365 Days of Astronomy no May 14th: Diamond Planet Finder Is A Star http://365daysofastronomy.org/2012/05/14/may-14th-diamond-planet-finder-is-a-star/ http://365daysofastronomy.org/2012/05/14/may-14th-diamond-planet-finder-is-a-star/#comments Mon, 14 May 2012 11:00:46 +0000 kortney.hogan http://365daysofastronomy.org/?p=7683 Date: May 14, 2012 Title: Diamond Planet Finder Is A Star Podcaster: Michael Greenwell Links: http://michaelgreenwell.wordpress.com/ and http://exitstageright.wordpress.com/ Description: Last year, after making an enormously publicized discovery astronomer Matthew Bailes used his moment of fame to defend his scientific colleagues and to try to point us in the direction in which we need to be looking. I think he should be applauded for this and we would do well to listen to what he had to say. Bio: Michael Greenwell has worked, at various times, as a university tutor, a barman, a DJ (not a very good one), an office lackey, supermarket worker, president of a small charity, a researcher, a librarian, a volunteer worker in Nepal during the civil war there, and some other things that were too tedious to mention. He blogs here and also runs the animal extinction site Exit Stage Right. Today's Sponsor: "This episode of 365 days of Astronomy is sponsored by 'The Heliochromologist' " "This episode of 365 days of astronomy was sponsored by iTelescope.net - Expanding your horizons in astronomy today. The premier on-demand telescope network, at dark sky sites in Spain, New Mexico and Siding Spring, Australia." Transcript: At the end of last August, you probably read about the scientists who found a planet that is, in their words “certainly crystalline” or in other words, a large…. well… ok…a VERY large diamond…in fact, it is about 4 times the diameter of the Earth. The planet orbits a pulsar, which they referred to as Beyonce on account of the amount of Bling it was showing off. The story got a lot of coverage but one of the scientists involved, Matthew Bailes, did something a couple of weeks later that was rather brave and just as worthy of note - and I think that he should be applauded for it and that we would do well to listen to what he had to say. Specifically, he wrote an article for an Australian website called “The Conversation” in which he used the opportunity the extensive media coverage this discovery gave him to defend climate scientists and try to draw people’s attention to a problem that is ever worsening ie the fact that while the media are happy to report about weird weather on Jupiter or Saturn for example, they show a certain reluctance to talk about Global Weirding and the problems of Climate change here on planet Earth. I’ll quote to you now a slightly shortened version of what he said…

Following the publication of our finding in the journal Science, our research received amazing attention from the world’s media. I was asked by many journalists about the significance of the discovery. If I were honest, I’d have to concede that, although worthy of publication in Science, in the field of astrophysics it isn’t that significant. And yet the diamond planet has been hugely successful in igniting public curiosity about the universe in which we live. Imagine for a minute that, instead of discovering a diamond planet, we’d made a breakthrough in global temperature projections. Let’s say we studied computer models of the influence of excessive greenhouse gases, verified them through observations, then had them peer-reviewed and published in Science. Instead of sitting back and basking in the glory, I suspect we’d find a lot of commentators, many with no scientific qualifications, pouring scorn on our findings. People on the fringe of science would be quoted as opponents of our work, arguing that it was nothing more than a theory yet to be conclusively proven. Before long our credibility and findings would be under serious question. But luckily we’re not climate scientists. It may come as a big surprise to many, but there is actually no difference between how science works in astronomy and climate change – or any other scientific discipline for that matter. We make observations, run simulations, test and propose hypotheses, and undergo peer review of our findings. Of course we all make mistakes. But eventually the prevailing wisdom of the community triumphs and the field advances. It’s wonderful to be a part of that process. But on occasion those from the fringe of the scientific community will push a position that is simply not credible against the weight of evidence. This occurs within any discipline. But it seems it’s only in the field of climate science that such people are given airtime and column inches to espouse their views. Those who want to ignore what’s happening to Earth feel they need to be able to quote “alternative studies”, regardless of the scientific merit of those studies. In all fields of science, papers are challenged and statistics are debated. If there is any basis to these challenges they stand, but if not they fall by the wayside and the field continues to advance. When big theories fall, it isn’t because of business or political pressures – it’s because of the scientific process. Sadly, the same media commentators who celebrate diamond planets without question are all too quick to dismiss the latest peer-reviewed evidence that suggests man-made activities are responsible for changes in concentrations of CO2 in our atmosphere. The scientific method is universal. If we selectively ignore it in certain disciplines, we do so at our peril.

"Should the free precession be accepted as the correct explanation of the phenomena, it will give an important tool to study white dwarf equations of state. The theory of compact objects predicts certain relations between the spin and precession periods, and our finding provides a good test for the theory and establishes a qualitative model to be explored both theoretically and observationally. Detection of precession can become a powerful tool in searching for the internal properties of compact stars, which would be otherwise inaccessible for us. Combined with other methods to estimate masses and density of the WDs in CVs, the precession period will help to refine these values, which in turn, allows for testing and proving the theory for the precession of compact stars and may allow for further advances in our knowledge of the structure of WDs and the influence of accretion on them."

Some interesting things were also observed in the quiescent state prompting additional scrutiny during this year's season of the longer term behaviour of the system when at quiescence. It has been great to be a part of the wonderful science research that is still ongoing. Its all part of the great science you can do as a part of any number of citizen science initiatives. The AAVSO and Variable Stars South have many and varied research projects just like this one where you can play a significant part in gathering the data and working with professional astronomers. It was great working with such professional people ably lead by Vitaly and George Sjoberg. Participation in campaigns like this is a great way to get to know other astronomers, and build your credibility as a capable amateur astronomer. End of podcast: 365 Days of Astronomy ===================== The 365 Days of Astronomy Podcast is produced by the Astrosphere New Media Association. Audio post-production by Preston Gibson. Bandwidth donated by libsyn.com and wizzard media. Web design by Clockwork Active Media Systems. You may reproduce and distribute this audio for non-commercial purposes. Please consider supporting the podcast with a few dollars (or Euros!). Visit us on the web at 365DaysOfAstronomy.org or email us at info@365DaysOfAstronomy.org. Until tomorrow...goodbye.]]> http://365daysofastronomy.org/2012/05/10/may-10th-twinkle-twinkle-little-star-how-i-wonder-fs-aur/feed/ 0 podcast iya 365 Date: May 10, 2012 - Title: Twinkle Twinkle little star ...... How I wonder FS Aur? - Podcaster: Peter Lake - Organization: AARTScope Blog - Links: http://aartscope.blogspot.com http://vitaly.neustroev.net/research/observing-campaigns/ http://www. Date: May 10, 2012 Title: Twinkle Twinkle little star ...... How I wonder FS Aur? Podcaster: Peter Lake Organization: AARTScope Blog Links: http://aartscope.blogspot.com http://vitaly.neustroev.net/research/observing-campaigns/ http://www.twitter.com/fs_Aur http://www.aavso.org Description: FS Aur is one of the most strangest and erratic variable Stars. Peter Lake reports on the data collected as part of the broader work with Dr Vitaly Neustroev of the Oulu University Finland and discusses the past two seasons of observations. Peter Lake is an Amateur Astronomer from Melbourne Australia and regularly discusses how people can be involved in citizen science and observation programs. Bio: Peter Lake is an amateur Astronomer from Melbourne, Australia, a member of Variable Stars South and the AAVSO and he owns and operates a 0.5m Planewave CDK Telescope at New Mexico skies, which is affiliated to iTelescope.net. Peter has been a participant in citizen science and recovered asteroid 2000 EV70 during the Spacewatch FMO program. More recently Peter has been actively involved in the study of cataclysmic variable star FS Aur, and followup exoplanet observations on Kepler targets of interest. Sponsor: "This episode of 365 days of astronomy is sponsored with thanks to all non-US contributors for showing us that the night sky is something we can all share." "Additional sponsorship for this episode of 365 days of astronomy was provided by iTelescope.net - Expanding your horizons in astronomy today. The premier on-demand telescope network, at dark sky sites in Spain, New Mexico and Siding Spring, Australia." Transcript: Like duck hunting, Variable Stars have their "Seasons" also. A season being where the variable star in question is in the optimal position for "shooting with CCDs" ie observable for most of the night, during this time ideally it can be visible for as many as 6-7 hours per night. FS Aur is a Cataclysmic Variable is now low in the west at sunset at the close of an intensive second season. So I though it would be good to review these past two seasons, before once again, it comes around for observations in the next northern winter. FS Aur is one of the strangest and complex objects in the extensive variable star family. It is thought to be a magnetic white dwarf and red giant binary Star with a third object acting on it in a circumbinary orbit. (Tovmassian et al., 2010) Back in 2010 there was a sporadic and incomplete light curve and astronomers wanted answers. When they want answers they often leverage the collective effort of the American Association of Variable Star Observers (AAVSO), to muscle up some more observations and data. FS Aur has a number of photometric and spectroscopic cycles going on. On top of this it goes into outburst about every 12-15 days. The outburst duration is so short (2-3 days) it has been regularly missed in the past - so in the 2010/11 season Dr Neustroev rallied a special effort. For the first time, members of the AAVSO mapped the entire outburst cycle, a good number of times. Dr Vitaly Neustroev is the University Researcher (Yliopistotutkija) at the University of Oulu, Finland and he is a key researcher on FS Aur, working hard to better understand its erratic behaviour. Visit the observing campaign page here, and also follow on (Twitter). I like following Cataclysmic Variables, after catching Simostronomy fever, and I have been a regular on FS Aur since Dr Neustroev's call to action. During the campaign FS Aur has been dancing away with a little periodic wobble at about 15.9 with the odd subtle change in brightness, then it goes really dull to 16.2 then literally within 24-36 hours it pops up to magnitude about Mag 14. As an amateur astronomer I am always careful to point out that I'm not qualified to say how or why, but I can tell you when, where and how bright! So what is going on with FS Aur - Dr Neustroev describes it this way: 365 Days of Astronomy no May 9th: Astronomy Word of the Week: Nova http://365daysofastronomy.org/2012/05/09/may-9th-astronomy-word-of-the-week-nova/ http://365daysofastronomy.org/2012/05/09/may-9th-astronomy-word-of-the-week-nova/#comments Wed, 09 May 2012 11:00:09 +0000 kortney.hogan http://365daysofastronomy.org/?p=7650 Date: May 9, 2012 Title: Astronomy Word of the Week: Nova Podcaster: Dr. Christopher Crockett Organization: United States Naval Observatory Links: http://christophercrockett.com http://astrowow.wordpress.com/ Description: Why do once invisible stars suddenly flare up and then slowly fade from view? The astronomy word of the week is "nova". Bio: Dr. Christopher Crockett is an astronomer at the United States Naval Observatory in Flagstaff, Arizona. His research involves searching for planets around very young stars (“only” a few million years old). It is hoped that the results from this research will help constrain models of planet formation and lead to a better understanding of where, when, and how often planets form. Chris is also passionate about astronomy outreach and education and will talk for hours about the Universe if you let him. Sponsors: Sponsorship for this episode of "365 days of Astronomy" is donated anonymously and dedicated to the men and women of NASA who strive to turn science fiction into science reality. Additional sponsorship for this episode has been provided by iTelescope.net - Expanding your horizons in astronomy today. The premier on-demand telescope network, at dark sky sites in Spain, New Mexico and Siding Spring, Australia. Transcript: In 1572, Danish astronomer Tycho Brahe, along with observers around the world, noticed a new star in the constellation Casseiopeia. Rivaling Venus as the brightest object in the night sky after the Moon, the unexpected guest remained visible for nearly two years before fading from view. The appearance of a new star was nothing short of revolutionary; astronomers long agreed that the celestial sphere was unchanging. A transient star challenged this assumption and suggested that the heavens were perhaps more dynamic than originally thought. The celestial intruder came to be known as a "nova" - after Tycho Brahe's extensive manuscript on the phenomenon - where he referred to the object simply by the latin term for a new star: "stella nova". While no one could have known it at the time, the new star was actually not new at all but rather a very old star experiencing a cataclysmic event. Most of the stars in the sky are not singular, like our Sun, but rather members of binary star systems - two stars locked in orbit around one another. Of this pair, one star is often more massive than its companion and therefore burns through its nuclear fuel at a faster rate. The heavier star reaches the end of its life before its sibling. When it does, the star inflates to become a red giant and sheds its outer layers into space leaving behind the hot, dense stellar core. The naked core, known as a "white dwarf", continues to orbit its stellar neighbor while taking the next few billion years to passively cool from a white-hot 100,000 degrees. In the case of close binary pairs, the white dwarf can actually siphon matter off of its companion. The intermingled gravitational fields of the two stars builds a bridge of predominately hydrogen gas spanning the distance between them. Gas from the still active star flows through this gravitational funnel and spills on to the surface of the white dwarf. The mass of the white dwarf controls the rate of mass accretion; if the rate is high enough, then something quite spectacular can happen. White dwarfs are an example of a rather exotic type of matter that physicists call "degenerate". Most gasses expand when you heat them up: the increasing temperature causes the molecules to zip around faster which in turn increases the gas pressure. At extreme densities - like those seen in the cores of stars - the gas behaves rather peculiarly. The pressure is no longer a slave to temperature: turn up the heat and the gas does not expand. This counterintuitive behavior is crucial to what happens next on the white dwarf's surface. As hydrogen from the donor star comes crashing down, the crushing force of gravity compresses it into a degenerate state and the intense radiation heats the gas to many millions of degrees. But having now obtained the properties of a degenerate gas, the newly acquired hydrogen shell doesn't expand in response to the rapid heating, but holds its pressure steady. And now things get interesting. At temperatures exceeding 16 million degrees Celsius, conditions on the surface mimic those deep in the cores of stars and a thermonuclear explosion is the result. Hydrogen is rapidly fused into helium and the resulting release of energy blows the outer hydrogen shell off the surface of the white dwarf at speeds exceeding ten million kilometers per hour. In mere days, the white dwarf can increase its brightness by 100,000 times. It can then take months - or in some cases years - for the star to slowly fade from view. Our Milky Way Galaxy experiences several dozen novae each year, only about ten of which are visible from Earth. A few are even visible to the naked eye. The most recent nova to be seen without the aid of binoculars or telescopes did so in the constellation Scorpius, reaching its peak brightness on February 17, 2007. Even more rare are what astronomers call "recurrent nova". Once the white dwarf has blown the hydrogen shell into space, the gas can slowly start building up again. These are novae that flare up repeatedly, sometimes once a year, sometimes once every couple of decades. In our whole galaxy, only ten novae are known to be recurrent. In the centuries since the new star of 1572, astronomers have come to realize that the event which gave novae their name was not what we know now as a nova. Up until early in the 20th century, a nova referred to any rapid brightening of a star. But there are many reasons stars suddenly flare into view. What Tycho saw was actually something far more powerful - a type of, aptly named, supernova. The supernova of 1572 was not the result of a flash of hydrogen burning on a white dwarf shell, but rather was caused by the complete detonation of a white dwarf. By stealing gas from a nearby companion slowly enough, the progenitor of the supernova delayed a nova flash while gradually increasing its temperature and pressure and eventually igniting hydrogen fusion throughout the interior of the once dead stellar core. With out the counterbalancing force of the rest of the star to throttle these reactions, the now violently active core obliterated itself in one of the most powerful explosions the Universe can produce. The event of 1572 ushered in a new era of astronomy, one in which the constancy of the celestial sphere could no longer be assumed. Novae - and their more powerful supernovae cousins - are constant reminders that we, in fact, live in a highly dynamic and energetic Universe. End of podcast: 365 Days of Astronomy ===================== The 365 Days of Astronomy Podcast is produced by the Astrosphere New Media Association. Audio post-production by Preston Gibson. Bandwidth donated by libsyn.com and wizzard media. Web design by Clockwork Active Media Systems. You may reproduce and distribute this audio for non-commercial purposes. Please consider supporting the podcast with a few dollars (or Euros!). Visit us on the web at 365DaysOfAstronomy.org or email us at info@365DaysOfAstronomy.org. Until tomorrow...goodbye.]]> http://365daysofastronomy.org/2012/05/09/may-9th-astronomy-word-of-the-week-nova/feed/ 0 podcast iya 365 Date: May 9, 2012 - Title: Astronomy Word of the Week: Nova - Podcaster: Dr. Christopher Crockett - Organization: United States Naval Observatory - Links: http://christophercrockett.com http://astrowow.wordpress.com/ - Date: May 9, 2012 Title: Astronomy Word of the Week: Nova Podcaster: Dr. Christopher Crockett Organization: United States Naval Observatory Links: http://christophercrockett.com http://astrowow.wordpress.com/ Description: Why do once invisible stars suddenly flare up and then slowly fade from view? The astronomy word of the week is "nova". Bio: Dr. Christopher Crockett is an astronomer at the United States Naval Observatory in Flagstaff, Arizona. His research involves searching for planets around very young stars (“only” a few million years old). It is hoped that the results from this research will help constrain models of planet formation and lead to a better understanding of where, when, and how often planets form. Chris is also passionate about astronomy outreach and education and will talk for hours about the Universe if you let him. Sponsors: Sponsorship for this episode of "365 days of Astronomy" is donated anonymously and dedicated to the men and women of NASA who strive to turn science fiction into science reality. Additional sponsorship for this episode has been provided by iTelescope.net - Expanding your horizons in astronomy today. The premier on-demand telescope network, at dark sky sites in Spain, New Mexico and Siding Spring, Australia. Transcript: In 1572, Danish astronomer Tycho Brahe, along with observers around the world, noticed a new star in the constellation Casseiopeia. Rivaling Venus as the brightest object in the night sky after the Moon, the unexpected guest remained visible for nearly two years before fading from view. The appearance of a new star was nothing short of revolutionary; astronomers long agreed that the celestial sphere was unchanging. A transient star challenged this assumption and suggested that the heavens were perhaps more dynamic than originally thought. The celestial intruder came to be known as a "nova" - after Tycho Brahe's extensive manuscript on the phenomenon - where he referred to the object simply by the latin term for a new star: "stella nova". While no one could have known it at the time, the new star was actually not new at all but rather a very old star experiencing a cataclysmic event. Most of the stars in the sky are not singular, like our Sun, but rather members of binary star systems - two stars locked in orbit around one another. Of this pair, one star is often more massive than its companion and therefore burns through its nuclear fuel at a faster rate. The heavier star reaches the end of its life before its sibling. When it does, the star inflates to become a red giant and sheds its outer layers into space leaving behind the hot, dense stellar core. The naked core, known as a "white dwarf", continues to orbit its stellar neighbor while taking the next few billion years to passively cool from a white-hot 100,000 degrees. In the case of close binary pairs, the white dwarf can actually siphon matter off of its companion. The intermingled gravitational fields of the two stars builds a bridge of predominately hydrogen gas spanning the distance between them. Gas from the still active star flows through this gravitational funnel and spills on to the surface of the white dwarf. The mass of the white dwarf controls the rate of mass accretion; if the rate is high enough, then something quite spectacular can happen. White dwarfs are an example of a rather exotic type of matter that physicists call "degenerate". Most gasses expand when you heat them up: the increasing temperature causes the molecules to zip around faster which in turn increases the gas pressure. At extreme densities - like those seen in the cores of stars - the gas behaves rather peculiarly. The pressure is no longer a slave to temperature: turn up the heat and the gas does not expand. This counterintuitive behavior is crucial to what happens next on the white dwarf's surface. As hydrogen from the donor star comes crashing down, 365 Days of Astronomy no May 8th: What is Black http://365daysofastronomy.org/2012/05/08/may-8th-what-is-black/ http://365daysofastronomy.org/2012/05/08/may-8th-what-is-black/#comments Tue, 08 May 2012 11:00:41 +0000 kortney.hogan http://365daysofastronomy.org/?p=7646 Date: May 8, 2012 Title: What is Black Podcaster: Rob Sparks & Dr. Steven Pompea Organization: NOAO Links: www.noao.edu Description: Most people think of black as a color, but black is really the absence of light. Truly black surfaces reflect almost none of the light that falls on them. In this podcast, Dr. Stephen Pompea discusses black surface, how they are produced and why they are important in astronomy and other sciences. Bio: Rob Sparks is a science education specialist in the EPO group at NOAO and works on the Galileoscope project (www.galileoscope.org), providing design, dissemination and professional development. He also pens a great blog at halfastro.wordpress.com. Dr. Stephen Pompea did his undergraduate work in physics, space physics, and astronomy at Rice University, his Master’s work in physics teaching at Colorado State University, and his Ph.D. in astronomy at the University of Arizona. He is currently the manager of the Education and Public Outreach Group at the National Optical Astronomy Observatory. Sponsor: This episode of the 365 Days of Astronomy podcast is sponsored by the National Optical Astronomy Observatory. NOAO is a US national research and development center for ground-based nighttime astronomy. We provide astronomers access to world-class observing facilities on a peer-reviewed basis. Our mission is to engage in programs to develop the next generation of telescopes, instruments, and software tools necessary to enable exploration and investigation through the observable Universe. For information on observing proposals or our public programs, please visit www.noao.edu for more information. "This episode has also been sponsored by the Lake County Astronomical Society: Celebrating 30 years of stellar service to members and the public." Transcript: *** Transcript coming soon. *** End of podcast: 365 Days of Astronomy ===================== The 365 Days of Astronomy Podcast is produced by the Astrosphere New Media Association. Audio post-production by Preston Gibson. Bandwidth donated by libsyn.com and wizzard media. Web design by Clockwork Active Media Systems. You may reproduce and distribute this audio for non-commercial purposes. Please consider supporting the podcast with a few dollars (or Euros!). Visit us on the web at 365DaysOfAstronomy.org or email us at info@365DaysOfAstronomy.org. Until tomorrow...goodbye.]]> http://365daysofastronomy.org/2012/05/08/may-8th-what-is-black/feed/ 0 podcast iya 365 Date: May 8, 2012 - Title: What is Black - Podcaster: Rob Sparks & Dr. Steven Pompea - Organization: NOAO - Links: www.noao.edu - Description: Most people think of black as a color, but black is really the absence of light. Date: May 8, 2012 Title: What is Black Podcaster: Rob Sparks & Dr. Steven Pompea Organization: NOAO Links: www.noao.edu Description: Most people think of black as a color, but black is really the absence of light. Truly black surfaces reflect almost none of the light that falls on them. In this podcast, Dr. Stephen Pompea discusses black surface, how they are produced and why they are important in astronomy and other sciences. Bio: Rob Sparks is a science education specialist in the EPO group at NOAO and works on the Galileoscope project (www.galileoscope.org), providing design, dissemination and professional development. He also pens a great blog at halfastro.wordpress.com. Dr. Stephen Pompea did his undergraduate work in physics, space physics, and astronomy at Rice University, his Master’s work in physics teaching at Colorado State University, and his Ph.D. in astronomy at the University of Arizona. He is currently the manager of the Education and Public Outreach Group at the National Optical Astronomy Observatory. Sponsor: This episode of the 365 Days of Astronomy podcast is sponsored by the National Optical Astronomy Observatory. NOAO is a US national research and development center for ground-based nighttime astronomy. We provide astronomers access to world-class observing facilities on a peer-reviewed basis. Our mission is to engage in programs to develop the next generation of telescopes, instruments, and software tools necessary to enable exploration and investigation through the observable Universe. For information on observing proposals or our public programs, please visit www.noao.edu for more information. "This episode has also been sponsored by the Lake County Astronomical Society: Celebrating 30 years of stellar service to members and the public." Transcript: *** Transcript coming soon. *** End of podcast: 365 Days of Astronomy ===================== The 365 Days of Astronomy Podcast is produced by the Astrosphere New Media Association. Audio post-production by Preston Gibson. Bandwidth donated by libsyn.com and wizzard media. Web design by Clockwork Active Media Systems. You may reproduce and distribute this audio for non-commercial purposes. Please consider supporting the podcast with a few dollars (or Euros!). Visit us on the web at 365DaysOfAstronomy.org or email us at info@365DaysOfAstronomy.org. Until tomorrow...goodbye. 365 Days of Astronomy no May 7th: The Late Heavy Bombardment — an Extended Version? http://365daysofastronomy.org/2012/05/16/may-16th-gps/ http://365daysofastronomy.org/2012/05/16/may-16th-gps/#comments Wed, 16 May 2012 11:00:41 +0000 kortney.hogan http://365daysofastronomy.org/?p=7689 Date: May 16, 2012 Title: GPS Podcaster: Steve Nerlich Organization: Cheap Astronomy Links: www.cheapastro.com Description: Cheap Astronomy once again demonstrates that pretty much everything in life has a connection to astronomy. Bio: Cheap Astronomy offers an educational website because in space no-one can hear you podcast. Today's Sponsor: "This episode of 365 days of Astronomy" is sponsored by the Lake County Astronomical Society: Celebrating 30 years of stellar service to members and the public." Additional sponsorship for this episode has also been provided by iTelescope.net - Expanding your horizons in astronomy today. The premier on-demand telescope network, at dark sky sites in Spain, New Mexico and Siding Spring, Australia. Transcript: Hi this is Steve Nerlich from Cheap Astronomy www.cheapastro.com and this is GPS OK – If you don’t have one, you know someone who does, so let’s skip the introductions and get straight down to the astronomy. A standard GPS configuration is a constellation of 24 GPS satellites. The satellites are all at an altitude of 20,200 km with an orbital period of 11 hours and 58 minutes – which means they do exactly 2 orbits for each time the Earth spins once on its axis. Four satellites each follow six orbital planes separated by 60 degrees which surround the Earth in an (airquotes) ‘birdcage’ of criss-crossing orbits. There a link to the relevant Wikipedia article from the Cheap Astronomy podcast page which has a nice animation of a GPS satellite constellation. At last count, there were actually 31 actively transmitting GPS satellites – with these extra number increasing location accuracy and redundancy. There’s been some recent media regarding a growing risk of dropping below the minimum 24 active satellites required to make GPS work effectively, but it remains to be seen if this risk will be realised in the face of the increasing economic importance of maintaining a working GPS system. A GPS satellite broadcasts a signal indicating where it is and the time the signal was broadcast – your receiver then determines, from the time it receives that signal, the distance travelled by the signal, knowing that, being a radio transmission, the signal travels at the speed of light. By making just four calculations from four satellites in the sky, your GPS receiver can then establish its position with respect to latitude, longitude and altitude. It’s all about the conjunction of spheres. Imagine one satellite broadcasting a radio signal. If you pick up that signal and determine it’s a 100 km away, all you really know is that you are somewhere on a surface of a sphere with a 100 km radius that has the satellite at its centre. If there’s two such satellites then you’ll know you are somewhere on the circumference of a circle representing the plane where the two spheres of radio broadcast overlap. Introduce a third satellite and you can narrow down your location to just two points in space which are the points where two differently orientated circle circumferences intersect. Potentially this may be enough to roughly determine your position since you can anticipate you will be on the one of those two points corresponding to the surface of the Earth. But for strictest accuracy – including accuracy in determining your altitude above sea level, the signal from a fourth satellite is required. And that is the idea of the constellation of GPS satellites. Keeping 24 satellites moving in the same orbit, tracing a birdcage of divergent paths around the globe ensures there will always be four satellites in the sky wherever you happen to be on Earth. Now when I say GPS satellites just have to broadcast where they are – actually knowing where they are is a whole separate operation, While the orbital period is predictable, knowing at what point they are on that orbit requires some very accurate time keeping – for which reason each satellite has an atomic clock. Nonetheless, even this isn’t enough, as the orbital paths of the satellites are subject to slight shifting due to the gravitational influence of the Sun and the Moon. To keep track of these changes the satellites are monitored from a fixed, known location on the Earth’s surface – a function currently managed by the 50th Space Wing of the US Airforce Space Command – seriously. Now, given that your GPS receiver is working out its distance from each of four satellites based solely on the time lag of a signal moving at the speed of light from a satellite just over 20,000 kilometres away – there is considerable potential for a margin of error that could see you driving over the embankment into a river when that sexy voice says ‘turn left now’. There are a range of methods to deal with various sources of error. Firstly your GPS receiver carries an electronic almanac of which satellite should be where since confusion can arise when the satellite radio signals get reflected off surroundings, such as tall buildings. This electronic almanac is constructed from calibration data received from the GPS satellites, although these data are generally relayed from a ground-based source – such as Airforce Space Command. The almanac helps your receiver distinguish between garbage signals and genuine GPS signals. The receiver also receives time checks from the satellites since, most GPS receivers determine time from a cheap (not that there’s anything wrong with that) quartz clock rather than the ultra-accurate atomic clocks of the satellites. Clock error is probably the biggest potential source of GPS error, which is why, even though you could almost get away with determining your position from just 3 satellites, it is the fourth reading (which we might call quadrangulation) that ensures the poorer accuracy of the GPS receiver’s clock is effectively accounted for. Interestingly, there’s also relativistic effects to account for, since the satellites move in a weaker gravity field (meaning by general relativity their clocks run faster), and they also move at speed relative to the surface of the Earth (meaning by special relativity their clocks run slower). It turns out that the nett effect is that the satellites’ clocks run about 38 microseconds per day faster than they would at the Earth’s surface. To account for this, the clocks are actually set to run at a slightly lower rate, to keep pace with clocks running on the Earth’s surface. In the world of atomic clocks, various time keeping callibrations are also required to account for changes in the rotation of the Earth – which is influenced by the tidal drag of the Moon , the inertia of the Earth’s molten interior and even the melting of glaciers. Overall, the Earth’s rotation is slowing, leading to a lengthening of a solar day. Consequently a leap second must be introduced to atomic timepieces which measure Universal Coordinated Time (known as UTC – because of the French). In fact, a leap second is required to be added to UTC every 18 months or so because each year (on average) the length of a solar day increases by about 0.002 seconds. The atomic clocks of GPS satellites were aligned to UTC in 1980 – but as of 2009, these atomic clocks in orbit now vary by 19 seconds and to keep it simple we just say they are running at GPS time. Various under-the-hood adjustments are made along the way so that your GPS receiver can tell you the local time wherever you happen to be – as well as telling you where you are of course to within… well, within 10 metres is the general benchmark, although this takes a few minutes to establish after the unit is turned on and the accuracy will degrade with tall trees or buildings around. So, you know, it’s a guide – not an absolute – it’s still a good idea to keep one eye on the road. Thanks for listening. This is Steve Nerlich from Cheap Astronomy, www.cheapastro.com. Cheap Astronomy offers an educational website where you can’t put a price on space. No ads, no profit, just good science. Bye. End of podcast: 365 Days of Astronomy ===================== The 365 Days of Astronomy Podcast is produced by the New Media Working Group of the International Year of Astronomy 2009. Audio post-production by Preston Gibson. Bandwidth donated by libsyn.com and wizzard media. Web design by Clockwork Active Media Systems. You may reproduce and distribute this audio for non-commercial purposes. Please consider supporting the podcast with a few dollars (or Euros!). Visit us on the web at 365DaysOfAstronomy.org or email us at info@365DaysOfAstronomy.org. Until tomorrow...goodbye.]]> http://365daysofastronomy.org/2012/05/16/may-16th-gps/feed/ 0 podcast iya 365 Date: May 16, 2012 - Title: GPS Podcaster: Steve Nerlich - Organization: Cheap Astronomy - Links: www.cheapastro.com - Description: Cheap Astronomy once again demonstrates that pretty much everything in life has a connection to astronomy. - Date: May 16, 2012 Title: GPS Podcaster: Steve Nerlich Organization: Cheap Astronomy Links: www.cheapastro.com Description: Cheap Astronomy once again demonstrates that pretty much everything in life has a connection to astronomy. B... 365 Days of Astronomy no 365 Days of Astronomy http://365daysofastronomy.org An astronomy podcast every day, all year Wed, 16 May 2012 11:00:41 +0000 en hourly 1 http://wordpress.org/?v=3.1 An astronomy podcast every day, all year 365 Days of Astronomy no An astronomy podcast every day, all year 365 Days of Astronomy http://365daysofastronomy.org/wp-content/plugins/powerpress/rss_default.jpg http://365daysofastronomy.org May 16th: GPS http://365daysofastronomy.org/2012/05/16/may-16th-gps/ http://365daysofastronomy.org/2012/05/16/may-16th-gps/#comments Wed, 16 May 2012 11:00:41 +0000 kortney.hogan http://365daysofastronomy.org/?p=7689 Date: May 16, 2012 Title: GPS Podcaster: Steve Nerlich Organization: Cheap Astronomy Links: www.cheapastro.com Description: Cheap Astronomy once again demonstrates that pretty much everything in life has a connection to astronomy. Bio: Cheap Astronomy offers an educational website because in space no-one can hear you podcast. Today's Sponsor: "This episode of 365 days of Astronomy" is sponsored by the Lake County Astronomical Society: Celebrating 30 years of stellar service to members and the public." Additional sponsorship for this episode has also been provided by iTelescope.net - Expanding your horizons in astronomy today. The premier on-demand telescope network, at dark sky sites in Spain, New Mexico and Siding Spring, Australia. Transcript: Hi this is Steve Nerlich from Cheap Astronomy www.cheapastro.com and this is GPS OK – If you don’t have one, you know someone who does, so let’s skip the introductions and get straight down to the astronomy. A standard GPS configuration is a constellation of 24 GPS satellites. The satellites are all at an altitude of 20,200 km with an orbital period of 11 hours and 58 minutes – which means they do exactly 2 orbits for each time the Earth spins once on its axis. Four satellites each follow six orbital planes separated by 60 degrees which surround the Earth in an (airquotes) ‘birdcage’ of criss-crossing orbits. There a link to the relevant Wikipedia article from the Cheap Astronomy podcast page which has a nice animation of a GPS satellite constellation. At last count, there were actually 31 actively transmitting GPS satellites – with these extra number increasing location accuracy and redundancy. There’s been some recent media regarding a growing risk of dropping below the minimum 24 active satellites required to make GPS work effectively, but it remains to be seen if this risk will be realised in the face of the increasing economic importance of maintaining a working GPS system. A GPS satellite broadcasts a signal indicating where it is and the time the signal was broadcast – your receiver then determines, from the time it receives that signal, the distance travelled by the signal, knowing that, being a radio transmission, the signal travels at the speed of light. By making just four calculations from four satellites in the sky, your GPS receiver can then establish its position with respect to latitude, longitude and altitude. It’s all about the conjunction of spheres. Imagine one satellite broadcasting a radio signal. If you pick up that signal and determine it’s a 100 km away, all you really know is that you are somewhere on a surface of a sphere with a 100 km radius that has the satellite at its centre. If there’s two such satellites then you’ll know you are somewhere on the circumference of a circle representing the plane where the two spheres of radio broadcast overlap. Introduce a third satellite and you can narrow down your location to just two points in space which are the points where two differently orientated circle circumferences intersect. Potentially this may be enough to roughly determine your position since you can anticipate you will be on the one of those two points corresponding to the surface of the Earth. But for strictest accuracy – including accuracy in determining your altitude above sea level, the signal from a fourth satellite is required. And that is the idea of the constellation of GPS satellites. Keeping 24 satellites moving in the same orbit, tracing a birdcage of divergent paths around the globe ensures there will always be four satellites in the sky wherever you happen to be on Earth. Now when I say GPS satellites just have to broadcast where they are – actually knowing where they are is a whole separate operation, While the orbital period is predictable, knowing at what point they are on that orbit requires some very accurate time keeping – for which reason each satellite has an atomic clock. Nonetheless, even this isn’t enough, as the orbital paths of the satellites are subject to slight shifting due to the gravitational influence of the Sun and the Moon. To keep track of these changes the satellites are monitored from a fixed, known location on the Earth’s surface – a function currently managed by the 50th Space Wing of the US Airforce Space Command – seriously. Now, given that your GPS receiver is working out its distance from each of four satellites based solely on the time lag of a signal moving at the speed of light from a satellite just over 20,000 kilometres away – there is considerable potential for a margin of error that could see you driving over the embankment into a river when that sexy voice says ‘turn left now’. There are a range of methods to deal with various sources of error. Firstly your GPS receiver carries an electronic almanac of which satellite should be where since confusion can arise when the satellite radio signals get reflected off surroundings, such as tall buildings. This electronic almanac is constructed from calibration data received from the GPS satellites, although these data are generally relayed from a ground-based source – such as Airforce Space Command. The almanac helps your receiver distinguish between garbage signals and genuine GPS signals. The receiver also receives time checks from the satellites since, most GPS receivers determine time from a cheap (not that there’s anything wrong with that) quartz clock rather than the ultra-accurate atomic clocks of the satellites. Clock error is probably the biggest potential source of GPS error, which is why, even though you could almost get away with determining your position from just 3 satellites, it is the fourth reading (which we might call quadrangulation) that ensures the poorer accuracy of the GPS receiver’s clock is effectively accounted for. Interestingly, there’s also relativistic effects to account for, since the satellites move in a weaker gravity field (meaning by general relativity their clocks run faster), and they also move at speed relative to the surface of the Earth (meaning by special relativity their clocks run slower). It turns out that the nett effect is that the satellites’ clocks run about 38 microseconds per day faster than they would at the Earth’s surface. To account for this, the clocks are actually set to run at a slightly lower rate, to keep pace with clocks running on the Earth’s surface. In the world of atomic clocks, various time keeping callibrations are also required to account for changes in the rotation of the Earth – which is influenced by the tidal drag of the Moon , the inertia of the Earth’s molten interior and even the melting of glaciers. Overall, the Earth’s rotation is slowing, leading to a lengthening of a solar day. Consequently a leap second must be introduced to atomic timepieces which measure Universal Coordinated Time (known as UTC – because of the French). In fact, a leap second is required to be added to UTC every 18 months or so because each year (on average) the length of a solar day increases by about 0.002 seconds. The atomic clocks of GPS satellites were aligned to UTC in 1980 – but as of 2009, these atomic clocks in orbit now vary by 19 seconds and to keep it simple we just say they are running at GPS time. Various under-the-hood adjustments are made along the way so that your GPS receiver can tell you the local time wherever you happen to be – as well as telling you where you are of course to within… well, within 10 metres is the general benchmark, although this takes a few minutes to establish after the unit is turned on and the accuracy will degrade with tall trees or buildings around. So, you know, it’s a guide – not an absolute – it’s still a good idea to keep one eye on the road. Thanks for listening. This is Steve Nerlich from Cheap Astronomy, www.cheapastro.com. Cheap Astronomy offers an educational website where you can’t put a price on space. No ads, no profit, just good science. Bye. End of podcast: 365 Days of Astronomy ===================== The 365 Days of Astronomy Podcast is produced by the New Media Working Group of the International Year of Astronomy 2009. Audio post-production by Preston Gibson. Bandwidth donated by libsyn.com and wizzard media. Web design by Clockwork Active Media Systems. You may reproduce and distribute this audio for non-commercial purposes. Please consider supporting the podcast with a few dollars (or Euros!). Visit us on the web at 365DaysOfAstronomy.org or email us at info@365DaysOfAstronomy.org. Until tomorrow...goodbye.]]> http://365daysofastronomy.org/2012/05/16/may-16th-gps/feed/ 0 podcast iya 365 Date: May 16, 2012 - Title: GPS Podcaster: Steve Nerlich - Organization: Cheap Astronomy - Links: www.cheapastro.com - Description: Cheap Astronomy once again demonstrates that pretty much everything in life has a connection to astronomy. - Date: May 16, 2012 Title: GPS Podcaster: Steve Nerlich Organization: Cheap Astronomy Links: www.cheapastro.com Description: Cheap Astronomy once again demonstrates that pretty much everything in life has a connection to astronomy. B... 365 Days of Astronomy no May 15th: Astronomy Word of the Week: Obliquity http://365daysofastronomy.org/2012/05/15/may-15th-astronomy-word-of-the-week-obliquity/ http://365daysofastronomy.org/2012/05/15/may-15th-astronomy-word-of-the-week-obliquity/#comments Tue, 15 May 2012 11:00:14 +0000 kortney.hogan http://365daysofastronomy.org/?p=7687 Date: May 15, 2012 Title: Astronomy Word of the Week: Obliquity Podcaster: Dr. Christopher Crockett Organization: United States Naval Observatory Links: http://christophercrockett.com http://astrowow.wordpress.com/ Description: The tilt of our planet is about much more than the seasons. The astronomy word of the week is "obliquity". Bio: Dr. Christopher Crockett is an astronomer at the United States Naval Observatory in Flagstaff, Arizona. His research involves searching for planets around very young stars (“only” a few million years old). It is hoped that the results from this research will help constrain models of planet formation and lead to a better understanding of where, when, and how often planets form. Chris is also passionate about astronomy outreach and education and will talk for hours about the Universe if you let him. Today's Sponsor: "This episode of 365 days of Astronomy" is sponsored by iTelescope.net - Expanding your horizons in astronomy today. The premier on-demand telescope network, at dark sky sites in Spain, New Mexico and Siding Spring, Australia. This episode has also been sponsored by Lake County Astronomical Society: Celebrating 30 years of stellar service to members and the public. Transcript: The planet you're standing on is not very steady. She bobs and wobbles, ducks and weaves, as she makes her annual trek around the Sun. Our home constantly struggles with forces both external and internal; the Sun, the Moon, and the planets tug her back and forth while shifting masses within force her to constantly find new balance. The tilt of our planet's axis - what astronomers call its obliquity - is one measure of this interplanetary tug-of-war. Obliquity measures how far over a planet or moon is tipped relative to its orbit; in the Earth's case, it's about 23 degrees. We feel the obliquity in the changing seasons. In June, the north pole is tipped towards the Sun. The northern hemisphere experiences longer days and more direct sunlight giving us warm summer days. In December, the north pole is tipped away from the Sun and everyone above the equator experiences the bitter chill of winter as the days get shorter and the sunlight reaches us more obliquely. The other planets in our solar system exhibit a wide range of obliquities. Mars, Saturn, and Neptune are all tipped by roughly the same amount as Earth. Mercury and Jupiter have hardly any obliquity at all - which means no seasons for them. Venus' obliquity is 177 degrees; it is almost completely upside down. Put another way, it rotates in the opposite direction from Earth. Were there ever to be a break in Venus' stifling cloud layer, native Venusians would see the Sun rise in the west and set in the east! Uranus is another strange character; his obliquity is 97 degrees. Uranus is lying on his side! This leads to some very strange days and seasons. Each pole of Uranus alternates between being in constant sunlight for 42 years, then perpetual darkness for another 42 years. Only a very thin strip along the equator experiences anything like day/night cycles that we experience - and even then the Sun is frequently sitting very low on the horizon. Astronomers aren't entirely certain how Venus and Uranus came to have such extreme obliquities. A leading hypothesis is that both experienced massive collisions at some point in their distant past, essentially knocking them over. A glancing blow from a minor planet isn't the only thing that can change an obliquity. The tilt of our planet's axis is drifting - ever so slightly - all the time. The poles actually trace out a rather complex dance over time scales ranging from minutes to thousands of centuries. Like a spinning top, our planet also wobbles - though it does so very slowly. Over a period of 26,000 years, the poles trace out a giant circle in the sky. Right now, the north pole points pretty close to the star Polaris. But over time that will change, and in some epochs it will be pointing at nothing at all. This wobble - or precession - doesn't change the amount of obliquity; it simply changes where in space the poles are pointing. The Moon, however, does tug on our planet's axis. In addition to rotation and precession, the Earth experiences something called nutation. This is a slight rocking of the Earth's axis caused by the changing positions of the Moon, the Sun, and all the other bodies in the solar system. With many players involved, the motion from nutation is fairly complex. The main component nods the planet by a couple hundred meters over a nearly 19 year cycle that is tied to how the Moon's orbit drifts around the Earth. Our planet also has to contend with forces much closer to home. Internal motions of magma, deep sea currents, changing ocean salinity, winds, melting ice sheets, and even earthquakes all conspire to constantly change the distribution of mass within the Earth. The planet responds by continuously shifting its spin axis - an effect known as polar motion. This is a bit different than nutation; it actually changes where on Earth the north and south poles are located. Hard as it may be to fathom, these are not fixed locations on the globe. The drift is very small - centimeters per year - but it does add a complex twist to understanding our planets motion in space. The presence of a large moon is believed to help stabilize our obliquity. The tilt does change by a few degrees over many millions of years, but manages to hold steady at around 20-25 degrees. Mars, conversely, appears to be going through a chaotic evolution in its obliquity. Computer simulations of its stability suggest that, over the past few million years, the Red Planet's tilt has oscillated wildly between zero and sixty degrees which may lead to drastic swings in the environment. Many astrobiologists - scientists who study the evolution and origin of life in a cosmic context - argue that our moon may be an essential ingredient for providing a stable environment within which life could thrive. Does this mean that the existence of complex life and advanced civilizations is dependent on the presence of a large satellite? That's hard to say. It is certainly plausible that our closest neighbor in space has been an indispensable partner in the evolution of our species. I'm continually amazed at how a simple concept - like the tilt of a planet - can actually lead down a labyrinthian path of subtleties. Studying Earth's obliquity, and the obliquity of all the other planets and moons, reveals much about the dynamics of our planet, the interplay of our home and neighboring worlds, and even the often times cataclysmic evolution of the solar system. While the subtleties are far removed from our day-to-day lives, our Earth's position in space actually is inseparable from the human experience. The June solstice is just over a month away. Whether you're bundling up for winter, or heading to the beach for summer, remember: the Earth's obliquity is the reason for the seasons! End of podcast: 365 Days of Astronomy ===================== The 365 Days of Astronomy Podcast is produced by the New Media Working Group of the International Year of Astronomy 2009. Audio post-production by Preston Gibson. Bandwidth donated by libsyn.com and wizzard media. Web design by Clockwork Active Media Systems. You may reproduce and distribute this audio for non-commercial purposes. Please consider supporting the podcast with a few dollars (or Euros!). Visit us on the web at 365DaysOfAstronomy.org or email us at info@365DaysOfAstronomy.org. Until tomorrow...goodbye.]]> http://365daysofastronomy.org/2012/05/15/may-15th-astronomy-word-of-the-week-obliquity/feed/ 0 podcast iya 365 Date: May 15, 2012 - Title: Astronomy Word of the Week: Obliquity Podcaster: Dr. Christopher Crockett - Organization: United States Naval Observatory - Links: http://christophercrockett.com http://astrowow.wordpress.com/ - Date: May 15, 2012 Title: Astronomy Word of the Week: Obliquity Podcaster: Dr. Christopher Crockett Organization: United States Naval Observatory Links: http://christophercrockett.com http://astrowow.wordpress.com/ Description: The tilt of our planet is about much more than the seasons. The astronomy word of the week is "obliquity". Bio: Dr. Christopher Crockett is an astronomer at the United States Naval Observatory in Flagstaff, Arizona. His research involves searching for planets around very young stars (“only” a few million years old). It is hoped that the results from this research will help constrain models of planet formation and lead to a better understanding of where, when, and how often planets form. Chris is also passionate about astronomy outreach and education and will talk for hours about the Universe if you let him. Today's Sponsor: "This episode of 365 days of Astronomy" is sponsored by iTelescope.net - Expanding your horizons in astronomy today. The premier on-demand telescope network, at dark sky sites in Spain, New Mexico and Siding Spring, Australia. This episode has also been sponsored by Lake County Astronomical Society: Celebrating 30 years of stellar service to members and the public. Transcript: The planet you're standing on is not very steady. She bobs and wobbles, ducks and weaves, as she makes her annual trek around the Sun. Our home constantly struggles with forces both external and internal; the Sun, the Moon, and the planets tug her back and forth while shifting masses within force her to constantly find new balance. The tilt of our planet's axis - what astronomers call its obliquity - is one measure of this interplanetary tug-of-war. Obliquity measures how far over a planet or moon is tipped relative to its orbit; in the Earth's case, it's about 23 degrees. We feel the obliquity in the changing seasons. In June, the north pole is tipped towards the Sun. The northern hemisphere experiences longer days and more direct sunlight giving us warm summer days. In December, the north pole is tipped away from the Sun and everyone above the equator experiences the bitter chill of winter as the days get shorter and the sunlight reaches us more obliquely. The other planets in our solar system exhibit a wide range of obliquities. Mars, Saturn, and Neptune are all tipped by roughly the same amount as Earth. Mercury and Jupiter have hardly any obliquity at all - which means no seasons for them. Venus' obliquity is 177 degrees; it is almost completely upside down. Put another way, it rotates in the opposite direction from Earth. Were there ever to be a break in Venus' stifling cloud layer, native Venusians would see the Sun rise in the west and set in the east! Uranus is another strange character; his obliquity is 97 degrees. Uranus is lying on his side! This leads to some very strange days and seasons. Each pole of Uranus alternates between being in constant sunlight for 42 years, then perpetual darkness for another 42 years. Only a very thin strip along the equator experiences anything like day/night cycles that we experience - and even then the Sun is frequently sitting very low on the horizon. Astronomers aren't entirely certain how Venus and Uranus came to have such extreme obliquities. A leading hypothesis is that both experienced massive collisions at some point in their distant past, essentially knocking them over. A glancing blow from a minor planet isn't the only thing that can change an obliquity. The tilt of our planet's axis is drifting - ever so slightly - all the time. The poles actually trace out a rather complex dance over time scales ranging from minutes to thousands of centuries. Like a spinning top, our planet also wobbles - though it does so very slowly. Over a period of 26,000 years, the poles trace out a giant circle in the sky. Right now, the north pole points pretty close to the star Polaris. 365 Days of Astronomy no May 14th: Diamond Planet Finder Is A Star http://365daysofastronomy.org/2012/05/14/may-14th-diamond-planet-finder-is-a-star/ http://365daysofastronomy.org/2012/05/14/may-14th-diamond-planet-finder-is-a-star/#comments Mon, 14 May 2012 11:00:46 +0000 kortney.hogan http://365daysofastronomy.org/?p=7683 Date: May 14, 2012 Title: Diamond Planet Finder Is A Star Podcaster: Michael Greenwell Links: http://michaelgreenwell.wordpress.com/ and http://exitstageright.wordpress.com/ Description: Last year, after making an enormously publicized discovery astronomer Matthew Bailes used his moment of fame to defend his scientific colleagues and to try to point us in the direction in which we need to be looking. I think he should be applauded for this and we would do well to listen to what he had to say. Bio: Michael Greenwell has worked, at various times, as a university tutor, a barman, a DJ (not a very good one), an office lackey, supermarket worker, president of a small charity, a researcher, a librarian, a volunteer worker in Nepal during the civil war there, and some other things that were too tedious to mention. He blogs here and also runs the animal extinction site Exit Stage Right. Today's Sponsor: "This episode of 365 days of Astronomy is sponsored by 'The Heliochromologist' " "This episode of 365 days of astronomy was sponsored by iTelescope.net - Expanding your horizons in astronomy today. The premier on-demand telescope network, at dark sky sites in Spain, New Mexico and Siding Spring, Australia." Transcript: At the end of last August, you probably read about the scientists who found a planet that is, in their words “certainly crystalline” or in other words, a large…. well… ok…a VERY large diamond…in fact, it is about 4 times the diameter of the Earth. The planet orbits a pulsar, which they referred to as Beyonce on account of the amount of Bling it was showing off. The story got a lot of coverage but one of the scientists involved, Matthew Bailes, did something a couple of weeks later that was rather brave and just as worthy of note - and I think that he should be applauded for it and that we would do well to listen to what he had to say. Specifically, he wrote an article for an Australian website called “The Conversation” in which he used the opportunity the extensive media coverage this discovery gave him to defend climate scientists and try to draw people’s attention to a problem that is ever worsening ie the fact that while the media are happy to report about weird weather on Jupiter or Saturn for example, they show a certain reluctance to talk about Global Weirding and the problems of Climate change here on planet Earth. I’ll quote to you now a slightly shortened version of what he said…

Following the publication of our finding in the journal Science, our research received amazing attention from the world’s media. I was asked by many journalists about the significance of the discovery. If I were honest, I’d have to concede that, although worthy of publication in Science, in the field of astrophysics it isn’t that significant. And yet the diamond planet has been hugely successful in igniting public curiosity about the universe in which we live. Imagine for a minute that, instead of discovering a diamond planet, we’d made a breakthrough in global temperature projections. Let’s say we studied computer models of the influence of excessive greenhouse gases, verified them through observations, then had them peer-reviewed and published in Science. Instead of sitting back and basking in the glory, I suspect we’d find a lot of commentators, many with no scientific qualifications, pouring scorn on our findings. People on the fringe of science would be quoted as opponents of our work, arguing that it was nothing more than a theory yet to be conclusively proven. Before long our credibility and findings would be under serious question. But luckily we’re not climate scientists. It may come as a big surprise to many, but there is actually no difference between how science works in astronomy and climate change – or any other scientific discipline for that matter. We make observations, run simulations, test and propose hypotheses, and undergo peer review of our findings. Of course we all make mistakes. But eventually the prevailing wisdom of the community triumphs and the field advances. It’s wonderful to be a part of that process. But on occasion those from the fringe of the scientific community will push a position that is simply not credible against the weight of evidence. This occurs within any discipline. But it seems it’s only in the field of climate science that such people are given airtime and column inches to espouse their views. Those who want to ignore what’s happening to Earth feel they need to be able to quote “alternative studies”, regardless of the scientific merit of those studies. In all fields of science, papers are challenged and statistics are debated. If there is any basis to these challenges they stand, but if not they fall by the wayside and the field continues to advance. When big theories fall, it isn’t because of business or political pressures – it’s because of the scientific process. Sadly, the same media commentators who celebrate diamond planets without question are all too quick to dismiss the latest peer-reviewed evidence that suggests man-made activities are responsible for changes in concentrations of CO2 in our atmosphere. The scientific method is universal. If we selectively ignore it in certain disciplines, we do so at our peril.

"Should the free precession be accepted as the correct explanation of the phenomena, it will give an important tool to study white dwarf equations of state. The theory of compact objects predicts certain relations between the spin and precession periods, and our finding provides a good test for the theory and establishes a qualitative model to be explored both theoretically and observationally. Detection of precession can become a powerful tool in searching for the internal properties of compact stars, which would be otherwise inaccessible for us. Combined with other methods to estimate masses and density of the WDs in CVs, the precession period will help to refine these values, which in turn, allows for testing and proving the theory for the precession of compact stars and may allow for further advances in our knowledge of the structure of WDs and the influence of accretion on them."

Some interesting things were also observed in the quiescent state prompting additional scrutiny during this year's season of the longer term behaviour of the system when at quiescence. It has been great to be a part of the wonderful science research that is still ongoing. Its all part of the great science you can do as a part of any number of citizen science initiatives. The AAVSO and Variable Stars South have many and varied research projects just like this one where you can play a significant part in gathering the data and working with professional astronomers. It was great working with such professional people ably lead by Vitaly and George Sjoberg. Participation in campaigns like this is a great way to get to know other astronomers, and build your credibility as a capable amateur astronomer. End of podcast: 365 Days of Astronomy ===================== The 365 Days of Astronomy Podcast is produced by the Astrosphere New Media Association. Audio post-production by Preston Gibson. Bandwidth donated by libsyn.com and wizzard media. Web design by Clockwork Active Media Systems. You may reproduce and distribute this audio for non-commercial purposes. Please consider supporting the podcast with a few dollars (or Euros!). Visit us on the web at 365DaysOfAstronomy.org or email us at info@365DaysOfAstronomy.org. Until tomorrow...goodbye.]]> http://365daysofastronomy.org/2012/05/10/may-10th-twinkle-twinkle-little-star-how-i-wonder-fs-aur/feed/ 0 podcast iya 365 Date: May 10, 2012 - Title: Twinkle Twinkle little star ...... How I wonder FS Aur? - Podcaster: Peter Lake - Organization: AARTScope Blog - Links: http://aartscope.blogspot.com http://vitaly.neustroev.net/research/observing-campaigns/ http://www. Date: May 10, 2012 Title: Twinkle Twinkle little star ...... How I wonder FS Aur? Podcaster: Peter Lake Organization: AARTScope Blog Links: http://aartscope.blogspot.com http://vitaly.neustroev.net/research/observing-campaigns/ http://www.twitter.com/fs_Aur http://www.aavso.org Description: FS Aur is one of the most strangest and erratic variable Stars. Peter Lake reports on the data collected as part of the broader work with Dr Vitaly Neustroev of the Oulu University Finland and discusses the past two seasons of observations. Peter Lake is an Amateur Astronomer from Melbourne Australia and regularly discusses how people can be involved in citizen science and observation programs. Bio: Peter Lake is an amateur Astronomer from Melbourne, Australia, a member of Variable Stars South and the AAVSO and he owns and operates a 0.5m Planewave CDK Telescope at New Mexico skies, which is affiliated to iTelescope.net. Peter has been a participant in citizen science and recovered asteroid 2000 EV70 during the Spacewatch FMO program. More recently Peter has been actively involved in the study of cataclysmic variable star FS Aur, and followup exoplanet observations on Kepler targets of interest. Sponsor: "This episode of 365 days of astronomy is sponsored with thanks to all non-US contributors for showing us that the night sky is something we can all share." "Additional sponsorship for this episode of 365 days of astronomy was provided by iTelescope.net - Expanding your horizons in astronomy today. The premier on-demand telescope network, at dark sky sites in Spain, New Mexico and Siding Spring, Australia." Transcript: Like duck hunting, Variable Stars have their "Seasons" also. A season being where the variable star in question is in the optimal position for "shooting with CCDs" ie observable for most of the night, during this time ideally it can be visible for as many as 6-7 hours per night. FS Aur is a Cataclysmic Variable is now low in the west at sunset at the close of an intensive second season. So I though it would be good to review these past two seasons, before once again, it comes around for observations in the next northern winter. FS Aur is one of the strangest and complex objects in the extensive variable star family. It is thought to be a magnetic white dwarf and red giant binary Star with a third object acting on it in a circumbinary orbit. (Tovmassian et al., 2010) Back in 2010 there was a sporadic and incomplete light curve and astronomers wanted answers. When they want answers they often leverage the collective effort of the American Association of Variable Star Observers (AAVSO), to muscle up some more observations and data. FS Aur has a number of photometric and spectroscopic cycles going on. On top of this it goes into outburst about every 12-15 days. The outburst duration is so short (2-3 days) it has been regularly missed in the past - so in the 2010/11 season Dr Neustroev rallied a special effort. For the first time, members of the AAVSO mapped the entire outburst cycle, a good number of times. Dr Vitaly Neustroev is the University Researcher (Yliopistotutkija) at the University of Oulu, Finland and he is a key researcher on FS Aur, working hard to better understand its erratic behaviour. Visit the observing campaign page here, and also follow on (Twitter). I like following Cataclysmic Variables, after catching Simostronomy fever, and I have been a regular on FS Aur since Dr Neustroev's call to action. During the campaign FS Aur has been dancing away with a little periodic wobble at about 15.9 with the odd subtle change in brightness, then it goes really dull to 16.2 then literally within 24-36 hours it pops up to magnitude about Mag 14. As an amateur astronomer I am always careful to point out that I'm not qualified to say how or why, but I can tell you when, where and how bright! So what is going on with FS Aur - Dr Neustroev describes it this way: 365 Days of Astronomy no May 9th: Astronomy Word of the Week: Nova http://365daysofastronomy.org/2012/05/09/may-9th-astronomy-word-of-the-week-nova/ http://365daysofastronomy.org/2012/05/09/may-9th-astronomy-word-of-the-week-nova/#comments Wed, 09 May 2012 11:00:09 +0000 kortney.hogan http://365daysofastronomy.org/?p=7650 Date: May 9, 2012 Title: Astronomy Word of the Week: Nova Podcaster: Dr. Christopher Crockett Organization: United States Naval Observatory Links: http://christophercrockett.com http://astrowow.wordpress.com/ Description: Why do once invisible stars suddenly flare up and then slowly fade from view? The astronomy word of the week is "nova". Bio: Dr. Christopher Crockett is an astronomer at the United States Naval Observatory in Flagstaff, Arizona. His research involves searching for planets around very young stars (“only” a few million years old). It is hoped that the results from this research will help constrain models of planet formation and lead to a better understanding of where, when, and how often planets form. Chris is also passionate about astronomy outreach and education and will talk for hours about the Universe if you let him. Sponsors: Sponsorship for this episode of "365 days of Astronomy" is donated anonymously and dedicated to the men and women of NASA who strive to turn science fiction into science reality. Additional sponsorship for this episode has been provided by iTelescope.net - Expanding your horizons in astronomy today. The premier on-demand telescope network, at dark sky sites in Spain, New Mexico and Siding Spring, Australia. Transcript: In 1572, Danish astronomer Tycho Brahe, along with observers around the world, noticed a new star in the constellation Casseiopeia. Rivaling Venus as the brightest object in the night sky after the Moon, the unexpected guest remained visible for nearly two years before fading from view. The appearance of a new star was nothing short of revolutionary; astronomers long agreed that the celestial sphere was unchanging. A transient star challenged this assumption and suggested that the heavens were perhaps more dynamic than originally thought. The celestial intruder came to be known as a "nova" - after Tycho Brahe's extensive manuscript on the phenomenon - where he referred to the object simply by the latin term for a new star: "stella nova". While no one could have known it at the time, the new star was actually not new at all but rather a very old star experiencing a cataclysmic event. Most of the stars in the sky are not singular, like our Sun, but rather members of binary star systems - two stars locked in orbit around one another. Of this pair, one star is often more massive than its companion and therefore burns through its nuclear fuel at a faster rate. The heavier star reaches the end of its life before its sibling. When it does, the star inflates to become a red giant and sheds its outer layers into space leaving behind the hot, dense stellar core. The naked core, known as a "white dwarf", continues to orbit its stellar neighbor while taking the next few billion years to passively cool from a white-hot 100,000 degrees. In the case of close binary pairs, the white dwarf can actually siphon matter off of its companion. The intermingled gravitational fields of the two stars builds a bridge of predominately hydrogen gas spanning the distance between them. Gas from the still active star flows through this gravitational funnel and spills on to the surface of the white dwarf. The mass of the white dwarf controls the rate of mass accretion; if the rate is high enough, then something quite spectacular can happen. White dwarfs are an example of a rather exotic type of matter that physicists call "degenerate". Most gasses expand when you heat them up: the increasing temperature causes the molecules to zip around faster which in turn increases the gas pressure. At extreme densities - like those seen in the cores of stars - the gas behaves rather peculiarly. The pressure is no longer a slave to temperature: turn up the heat and the gas does not expand. This counterintuitive behavior is crucial to what happens next on the white dwarf's surface. As hydrogen from the donor star comes crashing down, the crushing force of gravity compresses it into a degenerate state and the intense radiation heats the gas to many millions of degrees. But having now obtained the properties of a degenerate gas, the newly acquired hydrogen shell doesn't expand in response to the rapid heating, but holds its pressure steady. And now things get interesting. At temperatures exceeding 16 million degrees Celsius, conditions on the surface mimic those deep in the cores of stars and a thermonuclear explosion is the result. Hydrogen is rapidly fused into helium and the resulting release of energy blows the outer hydrogen shell off the surface of the white dwarf at speeds exceeding ten million kilometers per hour. In mere days, the white dwarf can increase its brightness by 100,000 times. It can then take months - or in some cases years - for the star to slowly fade from view. Our Milky Way Galaxy experiences several dozen novae each year, only about ten of which are visible from Earth. A few are even visible to the naked eye. The most recent nova to be seen without the aid of binoculars or telescopes did so in the constellation Scorpius, reaching its peak brightness on February 17, 2007. Even more rare are what astronomers call "recurrent nova". Once the white dwarf has blown the hydrogen shell into space, the gas can slowly start building up again. These are novae that flare up repeatedly, sometimes once a year, sometimes once every couple of decades. In our whole galaxy, only ten novae are known to be recurrent. In the centuries since the new star of 1572, astronomers have come to realize that the event which gave novae their name was not what we know now as a nova. Up until early in the 20th century, a nova referred to any rapid brightening of a star. But there are many reasons stars suddenly flare into view. What Tycho saw was actually something far more powerful - a type of, aptly named, supernova. The supernova of 1572 was not the result of a flash of hydrogen burning on a white dwarf shell, but rather was caused by the complete detonation of a white dwarf. By stealing gas from a nearby companion slowly enough, the progenitor of the supernova delayed a nova flash while gradually increasing its temperature and pressure and eventually igniting hydrogen fusion throughout the interior of the once dead stellar core. With out the counterbalancing force of the rest of the star to throttle these reactions, the now violently active core obliterated itself in one of the most powerful explosions the Universe can produce. The event of 1572 ushered in a new era of astronomy, one in which the constancy of the celestial sphere could no longer be assumed. Novae - and their more powerful supernovae cousins - are constant reminders that we, in fact, live in a highly dynamic and energetic Universe. End of podcast: 365 Days of Astronomy ===================== The 365 Days of Astronomy Podcast is produced by the Astrosphere New Media Association. Audio post-production by Preston Gibson. Bandwidth donated by libsyn.com and wizzard media. Web design by Clockwork Active Media Systems. You may reproduce and distribute this audio for non-commercial purposes. Please consider supporting the podcast with a few dollars (or Euros!). Visit us on the web at 365DaysOfAstronomy.org or email us at info@365DaysOfAstronomy.org. Until tomorrow...goodbye.]]> http://365daysofastronomy.org/2012/05/09/may-9th-astronomy-word-of-the-week-nova/feed/ 0 podcast iya 365 Date: May 9, 2012 - Title: Astronomy Word of the Week: Nova - Podcaster: Dr. Christopher Crockett - Organization: United States Naval Observatory - Links: http://christophercrockett.com http://astrowow.wordpress.com/ - Date: May 9, 2012 Title: Astronomy Word of the Week: Nova Podcaster: Dr. Christopher Crockett Organization: United States Naval Observatory Links: http://christophercrockett.com http://astrowow.wordpress.com/ Description: Why do once invisible stars suddenly flare up and then slowly fade from view? The astronomy word of the week is "nova". Bio: Dr. Christopher Crockett is an astronomer at the United States Naval Observatory in Flagstaff, Arizona. His research involves searching for planets around very young stars (“only” a few million years old). It is hoped that the results from this research will help constrain models of planet formation and lead to a better understanding of where, when, and how often planets form. Chris is also passionate about astronomy outreach and education and will talk for hours about the Universe if you let him. Sponsors: Sponsorship for this episode of "365 days of Astronomy" is donated anonymously and dedicated to the men and women of NASA who strive to turn science fiction into science reality. Additional sponsorship for this episode has been provided by iTelescope.net - Expanding your horizons in astronomy today. The premier on-demand telescope network, at dark sky sites in Spain, New Mexico and Siding Spring, Australia. Transcript: In 1572, Danish astronomer Tycho Brahe, along with observers around the world, noticed a new star in the constellation Casseiopeia. Rivaling Venus as the brightest object in the night sky after the Moon, the unexpected guest remained visible for nearly two years before fading from view. The appearance of a new star was nothing short of revolutionary; astronomers long agreed that the celestial sphere was unchanging. A transient star challenged this assumption and suggested that the heavens were perhaps more dynamic than originally thought. The celestial intruder came to be known as a "nova" - after Tycho Brahe's extensive manuscript on the phenomenon - where he referred to the object simply by the latin term for a new star: "stella nova". While no one could have known it at the time, the new star was actually not new at all but rather a very old star experiencing a cataclysmic event. Most of the stars in the sky are not singular, like our Sun, but rather members of binary star systems - two stars locked in orbit around one another. Of this pair, one star is often more massive than its companion and therefore burns through its nuclear fuel at a faster rate. The heavier star reaches the end of its life before its sibling. When it does, the star inflates to become a red giant and sheds its outer layers into space leaving behind the hot, dense stellar core. The naked core, known as a "white dwarf", continues to orbit its stellar neighbor while taking the next few billion years to passively cool from a white-hot 100,000 degrees. In the case of close binary pairs, the white dwarf can actually siphon matter off of its companion. The intermingled gravitational fields of the two stars builds a bridge of predominately hydrogen gas spanning the distance between them. Gas from the still active star flows through this gravitational funnel and spills on to the surface of the white dwarf. The mass of the white dwarf controls the rate of mass accretion; if the rate is high enough, then something quite spectacular can happen. White dwarfs are an example of a rather exotic type of matter that physicists call "degenerate". Most gasses expand when you heat them up: the increasing temperature causes the molecules to zip around faster which in turn increases the gas pressure. At extreme densities - like those seen in the cores of stars - the gas behaves rather peculiarly. The pressure is no longer a slave to temperature: turn up the heat and the gas does not expand. This counterintuitive behavior is crucial to what happens next on the white dwarf's surface. As hydrogen from the donor star comes crashing down, 365 Days of Astronomy no May 8th: What is Black http://365daysofastronomy.org/2012/05/08/may-8th-what-is-black/ http://365daysofastronomy.org/2012/05/08/may-8th-what-is-black/#comments Tue, 08 May 2012 11:00:41 +0000 kortney.hogan http://365daysofastronomy.org/?p=7646 Date: May 8, 2012 Title: What is Black Podcaster: Rob Sparks & Dr. Steven Pompea Organization: NOAO Links: www.noao.edu Description: Most people think of black as a color, but black is really the absence of light. Truly black surfaces reflect almost none of the light that falls on them. In this podcast, Dr. Stephen Pompea discusses black surface, how they are produced and why they are important in astronomy and other sciences. Bio: Rob Sparks is a science education specialist in the EPO group at NOAO and works on the Galileoscope project (www.galileoscope.org), providing design, dissemination and professional development. He also pens a great blog at halfastro.wordpress.com. Dr. Stephen Pompea did his undergraduate work in physics, space physics, and astronomy at Rice University, his Master’s work in physics teaching at Colorado State University, and his Ph.D. in astronomy at the University of Arizona. He is currently the manager of the Education and Public Outreach Group at the National Optical Astronomy Observatory. Sponsor: This episode of the 365 Days of Astronomy podcast is sponsored by the National Optical Astronomy Observatory. NOAO is a US national research and development center for ground-based nighttime astronomy. We provide astronomers access to world-class observing facilities on a peer-reviewed basis. Our mission is to engage in programs to develop the next generation of telescopes, instruments, and software tools necessary to enable exploration and investigation through the observable Universe. For information on observing proposals or our public programs, please visit www.noao.edu for more information. "This episode has also been sponsored by the Lake County Astronomical Society: Celebrating 30 years of stellar service to members and the public." Transcript: *** Transcript coming soon. *** End of podcast: 365 Days of Astronomy ===================== The 365 Days of Astronomy Podcast is produced by the Astrosphere New Media Association. Audio post-production by Preston Gibson. Bandwidth donated by libsyn.com and wizzard media. Web design by Clockwork Active Media Systems. You may reproduce and distribute this audio for non-commercial purposes. Please consider supporting the podcast with a few dollars (or Euros!). Visit us on the web at 365DaysOfAstronomy.org or email us at info@365DaysOfAstronomy.org. Until tomorrow...goodbye.]]> http://365daysofastronomy.org/2012/05/08/may-8th-what-is-black/feed/ 0 podcast iya 365 Date: May 8, 2012 - Title: What is Black - Podcaster: Rob Sparks & Dr. Steven Pompea - Organization: NOAO - Links: www.noao.edu - Description: Most people think of black as a color, but black is really the absence of light. Date: May 8, 2012 Title: What is Black Podcaster: Rob Sparks & Dr. Steven Pompea Organization: NOAO Links: www.noao.edu Description: Most people think of black as a color, but black is really the absence of light. Truly black surfaces reflect almost none of the light that falls on them. In this podcast, Dr. Stephen Pompea discusses black surface, how they are produced and why they are important in astronomy and other sciences. Bio: Rob Sparks is a science education specialist in the EPO group at NOAO and works on the Galileoscope project (www.galileoscope.org), providing design, dissemination and professional development. He also pens a great blog at halfastro.wordpress.com. Dr. Stephen Pompea did his undergraduate work in physics, space physics, and astronomy at Rice University, his Master’s work in physics teaching at Colorado State University, and his Ph.D. in astronomy at the University of Arizona. He is currently the manager of the Education and Public Outreach Group at the National Optical Astronomy Observatory. Sponsor: This episode of the 365 Days of Astronomy podcast is sponsored by the National Optical Astronomy Observatory. NOAO is a US national research and development center for ground-based nighttime astronomy. We provide astronomers access to world-class observing facilities on a peer-reviewed basis. Our mission is to engage in programs to develop the next generation of telescopes, instruments, and software tools necessary to enable exploration and investigation through the observable Universe. For information on observing proposals or our public programs, please visit www.noao.edu for more information. "This episode has also been sponsored by the Lake County Astronomical Society: Celebrating 30 years of stellar service to members and the public." Transcript: *** Transcript coming soon. *** End of podcast: 365 Days of Astronomy ===================== The 365 Days of Astronomy Podcast is produced by the Astrosphere New Media Association. Audio post-production by Preston Gibson. Bandwidth donated by libsyn.com and wizzard media. Web design by Clockwork Active Media Systems. You may reproduce and distribute this audio for non-commercial purposes. Please consider supporting the podcast with a few dollars (or Euros!). Visit us on the web at 365DaysOfAstronomy.org or email us at info@365DaysOfAstronomy.org. Until tomorrow...goodbye. 365 Days of Astronomy no May 7th: The Late Heavy Bombardment — an Extended Version? http://365daysofastronomy.org/2012/05/15/may-15th-astronomy-word-of-the-week-obliquity/ http://365daysofastronomy.org/2012/05/15/may-15th-astronomy-word-of-the-week-obliquity/#comments Tue, 15 May 2012 11:00:14 +0000 kortney.hogan http://365daysofastronomy.org/?p=7687 Date: May 15, 2012 Title: Astronomy Word of the Week: Obliquity Podcaster: Dr. Christopher Crockett Organization: United States Naval Observatory Links: http://christophercrockett.com http://astrowow.wordpress.com/ Description: The tilt of our planet is about much more than the seasons. The astronomy word of the week is "obliquity". Bio: Dr. Christopher Crockett is an astronomer at the United States Naval Observatory in Flagstaff, Arizona. His research involves searching for planets around very young stars (“only” a few million years old). It is hoped that the results from this research will help constrain models of planet formation and lead to a better understanding of where, when, and how often planets form. Chris is also passionate about astronomy outreach and education and will talk for hours about the Universe if you let him. Today's Sponsor: "This episode of 365 days of Astronomy" is sponsored by iTelescope.net - Expanding your horizons in astronomy today. The premier on-demand telescope network, at dark sky sites in Spain, New Mexico and Siding Spring, Australia. This episode has also been sponsored by Lake County Astronomical Society: Celebrating 30 years of stellar service to members and the public. Transcript: The planet you're standing on is not very steady. She bobs and wobbles, ducks and weaves, as she makes her annual trek around the Sun. Our home constantly struggles with forces both external and internal; the Sun, the Moon, and the planets tug her back and forth while shifting masses within force her to constantly find new balance. The tilt of our planet's axis - what astronomers call its obliquity - is one measure of this interplanetary tug-of-war. Obliquity measures how far over a planet or moon is tipped relative to its orbit; in the Earth's case, it's about 23 degrees. We feel the obliquity in the changing seasons. In June, the north pole is tipped towards the Sun. The northern hemisphere experiences longer days and more direct sunlight giving us warm summer days. In December, the north pole is tipped away from the Sun and everyone above the equator experiences the bitter chill of winter as the days get shorter and the sunlight reaches us more obliquely. The other planets in our solar system exhibit a wide range of obliquities. Mars, Saturn, and Neptune are all tipped by roughly the same amount as Earth. Mercury and Jupiter have hardly any obliquity at all - which means no seasons for them. Venus' obliquity is 177 degrees; it is almost completely upside down. Put another way, it rotates in the opposite direction from Earth. Were there ever to be a break in Venus' stifling cloud layer, native Venusians would see the Sun rise in the west and set in the east! Uranus is another strange character; his obliquity is 97 degrees. Uranus is lying on his side! This leads to some very strange days and seasons. Each pole of Uranus alternates between being in constant sunlight for 42 years, then perpetual darkness for another 42 years. Only a very thin strip along the equator experiences anything like day/night cycles that we experience - and even then the Sun is frequently sitting very low on the horizon. Astronomers aren't entirely certain how Venus and Uranus came to have such extreme obliquities. A leading hypothesis is that both experienced massive collisions at some point in their distant past, essentially knocking them over. A glancing blow from a minor planet isn't the only thing that can change an obliquity. The tilt of our planet's axis is drifting - ever so slightly - all the time. The poles actually trace out a rather complex dance over time scales ranging from minutes to thousands of centuries. Like a spinning top, our planet also wobbles - though it does so very slowly. Over a period of 26,000 years, the poles trace out a giant circle in the sky. Right now, the north pole points pretty close to the star Polaris. But over time that will change, and in some epochs it will be pointing at nothing at all. This wobble - or precession - doesn't change the amount of obliquity; it simply changes where in space the poles are pointing. The Moon, however, does tug on our planet's axis. In addition to rotation and precession, the Earth experiences something called nutation. This is a slight rocking of the Earth's axis caused by the changing positions of the Moon, the Sun, and all the other bodies in the solar system. With many players involved, the motion from nutation is fairly complex. The main component nods the planet by a couple hundred meters over a nearly 19 year cycle that is tied to how the Moon's orbit drifts around the Earth. Our planet also has to contend with forces much closer to home. Internal motions of magma, deep sea currents, changing ocean salinity, winds, melting ice sheets, and even earthquakes all conspire to constantly change the distribution of mass within the Earth. The planet responds by continuously shifting its spin axis - an effect known as polar motion. This is a bit different than nutation; it actually changes where on Earth the north and south poles are located. Hard as it may be to fathom, these are not fixed locations on the globe. The drift is very small - centimeters per year - but it does add a complex twist to understanding our planets motion in space. The presence of a large moon is believed to help stabilize our obliquity. The tilt does change by a few degrees over many millions of years, but manages to hold steady at around 20-25 degrees. Mars, conversely, appears to be going through a chaotic evolution in its obliquity. Computer simulations of its stability suggest that, over the past few million years, the Red Planet's tilt has oscillated wildly between zero and sixty degrees which may lead to drastic swings in the environment. Many astrobiologists - scientists who study the evolution and origin of life in a cosmic context - argue that our moon may be an essential ingredient for providing a stable environment within which life could thrive. Does this mean that the existence of complex life and advanced civilizations is dependent on the presence of a large satellite? That's hard to say. It is certainly plausible that our closest neighbor in space has been an indispensable partner in the evolution of our species. I'm continually amazed at how a simple concept - like the tilt of a planet - can actually lead down a labyrinthian path of subtleties. Studying Earth's obliquity, and the obliquity of all the other planets and moons, reveals much about the dynamics of our planet, the interplay of our home and neighboring worlds, and even the often times cataclysmic evolution of the solar system. While the subtleties are far removed from our day-to-day lives, our Earth's position in space actually is inseparable from the human experience. The June solstice is just over a month away. Whether you're bundling up for winter, or heading to the beach for summer, remember: the Earth's obliquity is the reason for the seasons! End of podcast: 365 Days of Astronomy ===================== The 365 Days of Astronomy Podcast is produced by the New Media Working Group of the International Year of Astronomy 2009. Audio post-production by Preston Gibson. Bandwidth donated by libsyn.com and wizzard media. Web design by Clockwork Active Media Systems. You may reproduce and distribute this audio for non-commercial purposes. Please consider supporting the podcast with a few dollars (or Euros!). Visit us on the web at 365DaysOfAstronomy.org or email us at info@365DaysOfAstronomy.org. Until tomorrow...goodbye.]]> http://365daysofastronomy.org/2012/05/15/may-15th-astronomy-word-of-the-week-obliquity/feed/ 0 podcast iya 365 Date: May 15, 2012 - Title: Astronomy Word of the Week: Obliquity Podcaster: Dr. Christopher Crockett - Organization: United States Naval Observatory - Links: http://christophercrockett.com http://astrowow.wordpress.com/ - Date: May 15, 2012 Title: Astronomy Word of the Week: Obliquity Podcaster: Dr. Christopher Crockett Organization: United States Naval Observatory Links: http://christophercrockett.com http://astrowow.wordpress.com/ Description: The tilt of our planet is about much more than the seasons. The astronomy word of the week is "obliquity". Bio: Dr. Christopher Crockett is an astronomer at the United States Naval Observatory in Flagstaff, Arizona. His research involves searching for planets around very young stars (“only” a few million years old). It is hoped that the results from this research will help constrain models of planet formation and lead to a better understanding of where, when, and how often planets form. Chris is also passionate about astronomy outreach and education and will talk for hours about the Universe if you let him. Today's Sponsor: "This episode of 365 days of Astronomy" is sponsored by iTelescope.net - Expanding your horizons in astronomy today. The premier on-demand telescope network, at dark sky sites in Spain, New Mexico and Siding Spring, Australia. This episode has also been sponsored by Lake County Astronomical Society: Celebrating 30 years of stellar service to members and the public. Transcript: The planet you're standing on is not very steady. She bobs and wobbles, ducks and weaves, as she makes her annual trek around the Sun. Our home constantly struggles with forces both external and internal; the Sun, the Moon, and the planets tug her back and forth while shifting masses within force her to constantly find new balance. The tilt of our planet's axis - what astronomers call its obliquity - is one measure of this interplanetary tug-of-war. Obliquity measures how far over a planet or moon is tipped relative to its orbit; in the Earth's case, it's about 23 degrees. We feel the obliquity in the changing seasons. In June, the north pole is tipped towards the Sun. The northern hemisphere experiences longer days and more direct sunlight giving us warm summer days. In December, the north pole is tipped away from the Sun and everyone above the equator experiences the bitter chill of winter as the days get shorter and the sunlight reaches us more obliquely. The other planets in our solar system exhibit a wide range of obliquities. Mars, Saturn, and Neptune are all tipped by roughly the same amount as Earth. Mercury and Jupiter have hardly any obliquity at all - which means no seasons for them. Venus' obliquity is 177 degrees; it is almost completely upside down. Put another way, it rotates in the opposite direction from Earth. Were there ever to be a break in Venus' stifling cloud layer, native Venusians would see the Sun rise in the west and set in the east! Uranus is another strange character; his obliquity is 97 degrees. Uranus is lying on his side! This leads to some very strange days and seasons. Each pole of Uranus alternates between being in constant sunlight for 42 years, then perpetual darkness for another 42 years. Only a very thin strip along the equator experiences anything like day/night cycles that we experience - and even then the Sun is frequently sitting very low on the horizon. Astronomers aren't entirely certain how Venus and Uranus came to have such extreme obliquities. A leading hypothesis is that both experienced massive collisions at some point in their distant past, essentially knocking them over. A glancing blow from a minor planet isn't the only thing that can change an obliquity. The tilt of our planet's axis is drifting - ever so slightly - all the time. The poles actually trace out a rather complex dance over time scales ranging from minutes to thousands of centuries. Like a spinning top, our planet also wobbles - though it does so very slowly. Over a period of 26,000 years, the poles trace out a giant circle in the sky. Right now, the north pole points pretty close to the star Polaris. 365 Days of Astronomy no 365 Days of Astronomy http://365daysofastronomy.org An astronomy podcast every day, all year Wed, 16 May 2012 11:00:41 +0000 en hourly 1 http://wordpress.org/?v=3.1 An astronomy podcast every day, all year 365 Days of Astronomy no An astronomy podcast every day, all year 365 Days of Astronomy http://365daysofastronomy.org/wp-content/plugins/powerpress/rss_default.jpg http://365daysofastronomy.org May 16th: GPS http://365daysofastronomy.org/2012/05/16/may-16th-gps/ http://365daysofastronomy.org/2012/05/16/may-16th-gps/#comments Wed, 16 May 2012 11:00:41 +0000 kortney.hogan http://365daysofastronomy.org/?p=7689 Date: May 16, 2012 Title: GPS Podcaster: Steve Nerlich Organization: Cheap Astronomy Links: www.cheapastro.com Description: Cheap Astronomy once again demonstrates that pretty much everything in life has a connection to astronomy. Bio: Cheap Astronomy offers an educational website because in space no-one can hear you podcast. Today's Sponsor: "This episode of 365 days of Astronomy" is sponsored by the Lake County Astronomical Society: Celebrating 30 years of stellar service to members and the public." Additional sponsorship for this episode has also been provided by iTelescope.net - Expanding your horizons in astronomy today. The premier on-demand telescope network, at dark sky sites in Spain, New Mexico and Siding Spring, Australia. Transcript: Hi this is Steve Nerlich from Cheap Astronomy www.cheapastro.com and this is GPS OK – If you don’t have one, you know someone who does, so let’s skip the introductions and get straight down to the astronomy. A standard GPS configuration is a constellation of 24 GPS satellites. The satellites are all at an altitude of 20,200 km with an orbital period of 11 hours and 58 minutes – which means they do exactly 2 orbits for each time the Earth spins once on its axis. Four satellites each follow six orbital planes separated by 60 degrees which surround the Earth in an (airquotes) ‘birdcage’ of criss-crossing orbits. There a link to the relevant Wikipedia article from the Cheap Astronomy podcast page which has a nice animation of a GPS satellite constellation. At last count, there were actually 31 actively transmitting GPS satellites – with these extra number increasing location accuracy and redundancy. There’s been some recent media regarding a growing risk of dropping below the minimum 24 active satellites required to make GPS work effectively, but it remains to be seen if this risk will be realised in the face of the increasing economic importance of maintaining a working GPS system. A GPS satellite broadcasts a signal indicating where it is and the time the signal was broadcast – your receiver then determines, from the time it receives that signal, the distance travelled by the signal, knowing that, being a radio transmission, the signal travels at the speed of light. By making just four calculations from four satellites in the sky, your GPS receiver can then establish its position with respect to latitude, longitude and altitude. It’s all about the conjunction of spheres. Imagine one satellite broadcasting a radio signal. If you pick up that signal and determine it’s a 100 km away, all you really know is that you are somewhere on a surface of a sphere with a 100 km radius that has the satellite at its centre. If there’s two such satellites then you’ll know you are somewhere on the circumference of a circle representing the plane where the two spheres of radio broadcast overlap. Introduce a third satellite and you can narrow down your location to just two points in space which are the points where two differently orientated circle circumferences intersect. Potentially this may be enough to roughly determine your position since you can anticipate you will be on the one of those two points corresponding to the surface of the Earth. But for strictest accuracy – including accuracy in determining your altitude above sea level, the signal from a fourth satellite is required. And that is the idea of the constellation of GPS satellites. Keeping 24 satellites moving in the same orbit, tracing a birdcage of divergent paths around the globe ensures there will always be four satellites in the sky wherever you happen to be on Earth. Now when I say GPS satellites just have to broadcast where they are – actually knowing where they are is a whole separate operation, While the orbital period is predictable, knowing at what point they are on that orbit requires some very accurate time keeping – for which reason each satellite has an atomic clock. Nonetheless, even this isn’t enough, as the orbital paths of the satellites are subject to slight shifting due to the gravitational influence of the Sun and the Moon. To keep track of these changes the satellites are monitored from a fixed, known location on the Earth’s surface – a function currently managed by the 50th Space Wing of the US Airforce Space Command – seriously. Now, given that your GPS receiver is working out its distance from each of four satellites based solely on the time lag of a signal moving at the speed of light from a satellite just over 20,000 kilometres away – there is considerable potential for a margin of error that could see you driving over the embankment into a river when that sexy voice says ‘turn left now’. There are a range of methods to deal with various sources of error. Firstly your GPS receiver carries an electronic almanac of which satellite should be where since confusion can arise when the satellite radio signals get reflected off surroundings, such as tall buildings. This electronic almanac is constructed from calibration data received from the GPS satellites, although these data are generally relayed from a ground-based source – such as Airforce Space Command. The almanac helps your receiver distinguish between garbage signals and genuine GPS signals. The receiver also receives time checks from the satellites since, most GPS receivers determine time from a cheap (not that there’s anything wrong with that) quartz clock rather than the ultra-accurate atomic clocks of the satellites. Clock error is probably the biggest potential source of GPS error, which is why, even though you could almost get away with determining your position from just 3 satellites, it is the fourth reading (which we might call quadrangulation) that ensures the poorer accuracy of the GPS receiver’s clock is effectively accounted for. Interestingly, there’s also relativistic effects to account for, since the satellites move in a weaker gravity field (meaning by general relativity their clocks run faster), and they also move at speed relative to the surface of the Earth (meaning by special relativity their clocks run slower). It turns out that the nett effect is that the satellites’ clocks run about 38 microseconds per day faster than they would at the Earth’s surface. To account for this, the clocks are actually set to run at a slightly lower rate, to keep pace with clocks running on the Earth’s surface. In the world of atomic clocks, various time keeping callibrations are also required to account for changes in the rotation of the Earth – which is influenced by the tidal drag of the Moon , the inertia of the Earth’s molten interior and even the melting of glaciers. Overall, the Earth’s rotation is slowing, leading to a lengthening of a solar day. Consequently a leap second must be introduced to atomic timepieces which measure Universal Coordinated Time (known as UTC – because of the French). In fact, a leap second is required to be added to UTC every 18 months or so because each year (on average) the length of a solar day increases by about 0.002 seconds. The atomic clocks of GPS satellites were aligned to UTC in 1980 – but as of 2009, these atomic clocks in orbit now vary by 19 seconds and to keep it simple we just say they are running at GPS time. Various under-the-hood adjustments are made along the way so that your GPS receiver can tell you the local time wherever you happen to be – as well as telling you where you are of course to within… well, within 10 metres is the general benchmark, although this takes a few minutes to establish after the unit is turned on and the accuracy will degrade with tall trees or buildings around. So, you know, it’s a guide – not an absolute – it’s still a good idea to keep one eye on the road. Thanks for listening. This is Steve Nerlich from Cheap Astronomy, www.cheapastro.com. Cheap Astronomy offers an educational website where you can’t put a price on space. No ads, no profit, just good science. Bye. End of podcast: 365 Days of Astronomy ===================== The 365 Days of Astronomy Podcast is produced by the New Media Working Group of the International Year of Astronomy 2009. Audio post-production by Preston Gibson. Bandwidth donated by libsyn.com and wizzard media. Web design by Clockwork Active Media Systems. You may reproduce and distribute this audio for non-commercial purposes. Please consider supporting the podcast with a few dollars (or Euros!). Visit us on the web at 365DaysOfAstronomy.org or email us at info@365DaysOfAstronomy.org. Until tomorrow...goodbye.]]> http://365daysofastronomy.org/2012/05/16/may-16th-gps/feed/ 0 podcast iya 365 Date: May 16, 2012 - Title: GPS Podcaster: Steve Nerlich - Organization: Cheap Astronomy - Links: www.cheapastro.com - Description: Cheap Astronomy once again demonstrates that pretty much everything in life has a connection to astronomy. - Date: May 16, 2012 Title: GPS Podcaster: Steve Nerlich Organization: Cheap Astronomy Links: www.cheapastro.com Description: Cheap Astronomy once again demonstrates that pretty much everything in life has a connection to astronomy. B... 365 Days of Astronomy no May 15th: Astronomy Word of the Week: Obliquity http://365daysofastronomy.org/2012/05/15/may-15th-astronomy-word-of-the-week-obliquity/ http://365daysofastronomy.org/2012/05/15/may-15th-astronomy-word-of-the-week-obliquity/#comments Tue, 15 May 2012 11:00:14 +0000 kortney.hogan http://365daysofastronomy.org/?p=7687 Date: May 15, 2012 Title: Astronomy Word of the Week: Obliquity Podcaster: Dr. Christopher Crockett Organization: United States Naval Observatory Links: http://christophercrockett.com http://astrowow.wordpress.com/ Description: The tilt of our planet is about much more than the seasons. The astronomy word of the week is "obliquity". Bio: Dr. Christopher Crockett is an astronomer at the United States Naval Observatory in Flagstaff, Arizona. His research involves searching for planets around very young stars (“only” a few million years old). It is hoped that the results from this research will help constrain models of planet formation and lead to a better understanding of where, when, and how often planets form. Chris is also passionate about astronomy outreach and education and will talk for hours about the Universe if you let him. Today's Sponsor: "This episode of 365 days of Astronomy" is sponsored by iTelescope.net - Expanding your horizons in astronomy today. The premier on-demand telescope network, at dark sky sites in Spain, New Mexico and Siding Spring, Australia. This episode has also been sponsored by Lake County Astronomical Society: Celebrating 30 years of stellar service to members and the public. Transcript: The planet you're standing on is not very steady. She bobs and wobbles, ducks and weaves, as she makes her annual trek around the Sun. Our home constantly struggles with forces both external and internal; the Sun, the Moon, and the planets tug her back and forth while shifting masses within force her to constantly find new balance. The tilt of our planet's axis - what astronomers call its obliquity - is one measure of this interplanetary tug-of-war. Obliquity measures how far over a planet or moon is tipped relative to its orbit; in the Earth's case, it's about 23 degrees. We feel the obliquity in the changing seasons. In June, the north pole is tipped towards the Sun. The northern hemisphere experiences longer days and more direct sunlight giving us warm summer days. In December, the north pole is tipped away from the Sun and everyone above the equator experiences the bitter chill of winter as the days get shorter and the sunlight reaches us more obliquely. The other planets in our solar system exhibit a wide range of obliquities. Mars, Saturn, and Neptune are all tipped by roughly the same amount as Earth. Mercury and Jupiter have hardly any obliquity at all - which means no seasons for them. Venus' obliquity is 177 degrees; it is almost completely upside down. Put another way, it rotates in the opposite direction from Earth. Were there ever to be a break in Venus' stifling cloud layer, native Venusians would see the Sun rise in the west and set in the east! Uranus is another strange character; his obliquity is 97 degrees. Uranus is lying on his side! This leads to some very strange days and seasons. Each pole of Uranus alternates between being in constant sunlight for 42 years, then perpetual darkness for another 42 years. Only a very thin strip along the equator experiences anything like day/night cycles that we experience - and even then the Sun is frequently sitting very low on the horizon. Astronomers aren't entirely certain how Venus and Uranus came to have such extreme obliquities. A leading hypothesis is that both experienced massive collisions at some point in their distant past, essentially knocking them over. A glancing blow from a minor planet isn't the only thing that can change an obliquity. The tilt of our planet's axis is drifting - ever so slightly - all the time. The poles actually trace out a rather complex dance over time scales ranging from minutes to thousands of centuries. Like a spinning top, our planet also wobbles - though it does so very slowly. Over a period of 26,000 years, the poles trace out a giant circle in the sky. Right now, the north pole points pretty close to the star Polaris. But over time that will change, and in some epochs it will be pointing at nothing at all. This wobble - or precession - doesn't change the amount of obliquity; it simply changes where in space the poles are pointing. The Moon, however, does tug on our planet's axis. In addition to rotation and precession, the Earth experiences something called nutation. This is a slight rocking of the Earth's axis caused by the changing positions of the Moon, the Sun, and all the other bodies in the solar system. With many players involved, the motion from nutation is fairly complex. The main component nods the planet by a couple hundred meters over a nearly 19 year cycle that is tied to how the Moon's orbit drifts around the Earth. Our planet also has to contend with forces much closer to home. Internal motions of magma, deep sea currents, changing ocean salinity, winds, melting ice sheets, and even earthquakes all conspire to constantly change the distribution of mass within the Earth. The planet responds by continuously shifting its spin axis - an effect known as polar motion. This is a bit different than nutation; it actually changes where on Earth the north and south poles are located. Hard as it may be to fathom, these are not fixed locations on the globe. The drift is very small - centimeters per year - but it does add a complex twist to understanding our planets motion in space. The presence of a large moon is believed to help stabilize our obliquity. The tilt does change by a few degrees over many millions of years, but manages to hold steady at around 20-25 degrees. Mars, conversely, appears to be going through a chaotic evolution in its obliquity. Computer simulations of its stability suggest that, over the past few million years, the Red Planet's tilt has oscillated wildly between zero and sixty degrees which may lead to drastic swings in the environment. Many astrobiologists - scientists who study the evolution and origin of life in a cosmic context - argue that our moon may be an essential ingredient for providing a stable environment within which life could thrive. Does this mean that the existence of complex life and advanced civilizations is dependent on the presence of a large satellite? That's hard to say. It is certainly plausible that our closest neighbor in space has been an indispensable partner in the evolution of our species. I'm continually amazed at how a simple concept - like the tilt of a planet - can actually lead down a labyrinthian path of subtleties. Studying Earth's obliquity, and the obliquity of all the other planets and moons, reveals much about the dynamics of our planet, the interplay of our home and neighboring worlds, and even the often times cataclysmic evolution of the solar system. While the subtleties are far removed from our day-to-day lives, our Earth's position in space actually is inseparable from the human experience. The June solstice is just over a month away. Whether you're bundling up for winter, or heading to the beach for summer, remember: the Earth's obliquity is the reason for the seasons! End of podcast: 365 Days of Astronomy ===================== The 365 Days of Astronomy Podcast is produced by the New Media Working Group of the International Year of Astronomy 2009. Audio post-production by Preston Gibson. Bandwidth donated by libsyn.com and wizzard media. Web design by Clockwork Active Media Systems. You may reproduce and distribute this audio for non-commercial purposes. Please consider supporting the podcast with a few dollars (or Euros!). Visit us on the web at 365DaysOfAstronomy.org or email us at info@365DaysOfAstronomy.org. Until tomorrow...goodbye.]]> http://365daysofastronomy.org/2012/05/15/may-15th-astronomy-word-of-the-week-obliquity/feed/ 0 podcast iya 365 Date: May 15, 2012 - Title: Astronomy Word of the Week: Obliquity Podcaster: Dr. Christopher Crockett - Organization: United States Naval Observatory - Links: http://christophercrockett.com http://astrowow.wordpress.com/ - Date: May 15, 2012 Title: Astronomy Word of the Week: Obliquity Podcaster: Dr. Christopher Crockett Organization: United States Naval Observatory Links: http://christophercrockett.com http://astrowow.wordpress.com/ Description: The tilt of our planet is about much more than the seasons. The astronomy word of the week is "obliquity". Bio: Dr. Christopher Crockett is an astronomer at the United States Naval Observatory in Flagstaff, Arizona. His research involves searching for planets around very young stars (“only” a few million years old). It is hoped that the results from this research will help constrain models of planet formation and lead to a better understanding of where, when, and how often planets form. Chris is also passionate about astronomy outreach and education and will talk for hours about the Universe if you let him. Today's Sponsor: "This episode of 365 days of Astronomy" is sponsored by iTelescope.net - Expanding your horizons in astronomy today. The premier on-demand telescope network, at dark sky sites in Spain, New Mexico and Siding Spring, Australia. This episode has also been sponsored by Lake County Astronomical Society: Celebrating 30 years of stellar service to members and the public. Transcript: The planet you're standing on is not very steady. She bobs and wobbles, ducks and weaves, as she makes her annual trek around the Sun. Our home constantly struggles with forces both external and internal; the Sun, the Moon, and the planets tug her back and forth while shifting masses within force her to constantly find new balance. The tilt of our planet's axis - what astronomers call its obliquity - is one measure of this interplanetary tug-of-war. Obliquity measures how far over a planet or moon is tipped relative to its orbit; in the Earth's case, it's about 23 degrees. We feel the obliquity in the changing seasons. In June, the north pole is tipped towards the Sun. The northern hemisphere experiences longer days and more direct sunlight giving us warm summer days. In December, the north pole is tipped away from the Sun and everyone above the equator experiences the bitter chill of winter as the days get shorter and the sunlight reaches us more obliquely. The other planets in our solar system exhibit a wide range of obliquities. Mars, Saturn, and Neptune are all tipped by roughly the same amount as Earth. Mercury and Jupiter have hardly any obliquity at all - which means no seasons for them. Venus' obliquity is 177 degrees; it is almost completely upside down. Put another way, it rotates in the opposite direction from Earth. Were there ever to be a break in Venus' stifling cloud layer, native Venusians would see the Sun rise in the west and set in the east! Uranus is another strange character; his obliquity is 97 degrees. Uranus is lying on his side! This leads to some very strange days and seasons. Each pole of Uranus alternates between being in constant sunlight for 42 years, then perpetual darkness for another 42 years. Only a very thin strip along the equator experiences anything like day/night cycles that we experience - and even then the Sun is frequently sitting very low on the horizon. Astronomers aren't entirely certain how Venus and Uranus came to have such extreme obliquities. A leading hypothesis is that both experienced massive collisions at some point in their distant past, essentially knocking them over. A glancing blow from a minor planet isn't the only thing that can change an obliquity. The tilt of our planet's axis is drifting - ever so slightly - all the time. The poles actually trace out a rather complex dance over time scales ranging from minutes to thousands of centuries. Like a spinning top, our planet also wobbles - though it does so very slowly. Over a period of 26,000 years, the poles trace out a giant circle in the sky. Right now, the north pole points pretty close to the star Polaris. 365 Days of Astronomy no May 14th: Diamond Planet Finder Is A Star http://365daysofastronomy.org/2012/05/14/may-14th-diamond-planet-finder-is-a-star/ http://365daysofastronomy.org/2012/05/14/may-14th-diamond-planet-finder-is-a-star/#comments Mon, 14 May 2012 11:00:46 +0000 kortney.hogan http://365daysofastronomy.org/?p=7683 Date: May 14, 2012 Title: Diamond Planet Finder Is A Star Podcaster: Michael Greenwell Links: http://michaelgreenwell.wordpress.com/ and http://exitstageright.wordpress.com/ Description: Last year, after making an enormously publicized discovery astronomer Matthew Bailes used his moment of fame to defend his scientific colleagues and to try to point us in the direction in which we need to be looking. I think he should be applauded for this and we would do well to listen to what he had to say. Bio: Michael Greenwell has worked, at various times, as a university tutor, a barman, a DJ (not a very good one), an office lackey, supermarket worker, president of a small charity, a researcher, a librarian, a volunteer worker in Nepal during the civil war there, and some other things that were too tedious to mention. He blogs here and also runs the animal extinction site Exit Stage Right. Today's Sponsor: "This episode of 365 days of Astronomy is sponsored by 'The Heliochromologist' " "This episode of 365 days of astronomy was sponsored by iTelescope.net - Expanding your horizons in astronomy today. The premier on-demand telescope network, at dark sky sites in Spain, New Mexico and Siding Spring, Australia." Transcript: At the end of last August, you probably read about the scientists who found a planet that is, in their words “certainly crystalline” or in other words, a large…. well… ok…a VERY large diamond…in fact, it is about 4 times the diameter of the Earth. The planet orbits a pulsar, which they referred to as Beyonce on account of the amount of Bling it was showing off. The story got a lot of coverage but one of the scientists involved, Matthew Bailes, did something a couple of weeks later that was rather brave and just as worthy of note - and I think that he should be applauded for it and that we would do well to listen to what he had to say. Specifically, he wrote an article for an Australian website called “The Conversation” in which he used the opportunity the extensive media coverage this discovery gave him to defend climate scientists and try to draw people’s attention to a problem that is ever worsening ie the fact that while the media are happy to report about weird weather on Jupiter or Saturn for example, they show a certain reluctance to talk about Global Weirding and the problems of Climate change here on planet Earth. I’ll quote to you now a slightly shortened version of what he said…

Following the publication of our finding in the journal Science, our research received amazing attention from the world’s media. I was asked by many journalists about the significance of the discovery. If I were honest, I’d have to concede that, although worthy of publication in Science, in the field of astrophysics it isn’t that significant. And yet the diamond planet has been hugely successful in igniting public curiosity about the universe in which we live. Imagine for a minute that, instead of discovering a diamond planet, we’d made a breakthrough in global temperature projections. Let’s say we studied computer models of the influence of excessive greenhouse gases, verified them through observations, then had them peer-reviewed and published in Science. Instead of sitting back and basking in the glory, I suspect we’d find a lot of commentators, many with no scientific qualifications, pouring scorn on our findings. People on the fringe of science would be quoted as opponents of our work, arguing that it was nothing more than a theory yet to be conclusively proven. Before long our credibility and findings would be under serious question. But luckily we’re not climate scientists. It may come as a big surprise to many, but there is actually no difference between how science works in astronomy and climate change – or any other scientific discipline for that matter. We make observations, run simulations, test and propose hypotheses, and undergo peer review of our findings. Of course we all make mistakes. But eventually the prevailing wisdom of the community triumphs and the field advances. It’s wonderful to be a part of that process. But on occasion those from the fringe of the scientific community will push a position that is simply not credible against the weight of evidence. This occurs within any discipline. But it seems it’s only in the field of climate science that such people are given airtime and column inches to espouse their views. Those who want to ignore what’s happening to Earth feel they need to be able to quote “alternative studies”, regardless of the scientific merit of those studies. In all fields of science, papers are challenged and statistics are debated. If there is any basis to these challenges they stand, but if not they fall by the wayside and the field continues to advance. When big theories fall, it isn’t because of business or political pressures – it’s because of the scientific process. Sadly, the same media commentators who celebrate diamond planets without question are all too quick to dismiss the latest peer-reviewed evidence that suggests man-made activities are responsible for changes in concentrations of CO2 in our atmosphere. The scientific method is universal. If we selectively ignore it in certain disciplines, we do so at our peril.

"Should the free precession be accepted as the correct explanation of the phenomena, it will give an important tool to study white dwarf equations of state. The theory of compact objects predicts certain relations between the spin and precession periods, and our finding provides a good test for the theory and establishes a qualitative model to be explored both theoretically and observationally. Detection of precession can become a powerful tool in searching for the internal properties of compact stars, which would be otherwise inaccessible for us. Combined with other methods to estimate masses and density of the WDs in CVs, the precession period will help to refine these values, which in turn, allows for testing and proving the theory for the precession of compact stars and may allow for further advances in our knowledge of the structure of WDs and the influence of accretion on them."

Following the publication of our finding in the journal Science, our research received amazing attention from the world’s media. I was asked by many journalists about the significance of the discovery. If I were honest, I’d have to concede that, although worthy of publication in Science, in the field of astrophysics it isn’t that significant. And yet the diamond planet has been hugely successful in igniting public curiosity about the universe in which we live. Imagine for a minute that, instead of discovering a diamond planet, we’d made a breakthrough in global temperature projections. Let’s say we studied computer models of the influence of excessive greenhouse gases, verified them through observations, then had them peer-reviewed and published in Science. Instead of sitting back and basking in the glory, I suspect we’d find a lot of commentators, many with no scientific qualifications, pouring scorn on our findings. People on the fringe of science would be quoted as opponents of our work, arguing that it was nothing more than a theory yet to be conclusively proven. Before long our credibility and findings would be under serious question. But luckily we’re not climate scientists. It may come as a big surprise to many, but there is actually no difference between how science works in astronomy and climate change – or any other scientific discipline for that matter. We make observations, run simulations, test and propose hypotheses, and undergo peer review of our findings. Of course we all make mistakes. But eventually the prevailing wisdom of the community triumphs and the field advances. It’s wonderful to be a part of that process. But on occasion those from the fringe of the scientific community will push a position that is simply not credible against the weight of evidence. This occurs within any discipline. But it seems it’s only in the field of climate science that such people are given airtime and column inches to espouse their views. Those who want to ignore what’s happening to Earth feel they need to be able to quote “alternative studies”, regardless of the scientific merit of those studies. In all fields of science, papers are challenged and statistics are debated. If there is any basis to these challenges they stand, but if not they fall by the wayside and the field continues to advance. When big theories fall, it isn’t because of business or political pressures – it’s because of the scientific process. Sadly, the same media commentators who celebrate diamond planets without question are all too quick to dismiss the latest peer-reviewed evidence that suggests man-made activities are responsible for changes in concentrations of CO2 in our atmosphere. The scientific method is universal. If we selectively ignore it in certain disciplines, we do so at our peril.

"Should the free precession be accepted as the correct explanation of the phenomena, it will give an important tool to study white dwarf equations of state. The theory of compact objects predicts certain relations between the spin and precession periods, and our finding provides a good test for the theory and establishes a qualitative model to be explored both theoretically and observationally. Detection of precession can become a powerful tool in searching for the internal properties of compact stars, which would be otherwise inaccessible for us. Combined with other methods to estimate masses and density of the WDs in CVs, the precession period will help to refine these values, which in turn, allows for testing and proving the theory for the precession of compact stars and may allow for further advances in our knowledge of the structure of WDs and the influence of accretion on them."

Some interesting things were also observed in the quiescent state prompting additional scrutiny during this year's season of the longer term behaviour of the system when at quiescence. It has been great to be a part of the wonderful science research that is still ongoing. Its all part of the great science you can do as a part of any number of citizen science initiatives. The AAVSO and Variable Stars South have many and varied research projects just like this one where you can play a significant part in gathering the data and working with professional astronomers. It was great working with such professional people ably lead by Vitaly and George Sjoberg. Participation in campaigns like this is a great way to get to know other astronomers, and build your credibility as a capable amateur astronomer. End of podcast: 365 Days of Astronomy ===================== The 365 Days of Astronomy Podcast is produced by the Astrosphere New Media Association. Audio post-production by Preston Gibson. Bandwidth donated by libsyn.com and wizzard media. Web design by Clockwork Active Media Systems. You may reproduce and distribute this audio for non-commercial purposes. Please consider supporting the podcast with a few dollars (or Euros!). Visit us on the web at 365DaysOfAstronomy.org or email us at info@365DaysOfAstronomy.org. Until tomorrow...goodbye.]]> http://365daysofastronomy.org/2012/05/10/may-10th-twinkle-twinkle-little-star-how-i-wonder-fs-aur/feed/ 0 podcast iya 365 Date: May 10, 2012 - Title: Twinkle Twinkle little star ...... How I wonder FS Aur? - Podcaster: Peter Lake - Organization: AARTScope Blog - Links: http://aartscope.blogspot.com http://vitaly.neustroev.net/research/observing-campaigns/ http://www. Date: May 10, 2012 Title: Twinkle Twinkle little star ...... How I wonder FS Aur? Podcaster: Peter Lake Organization: AARTScope Blog Links: http://aartscope.blogspot.com http://vitaly.neustroev.net/research/observing-campaigns/ http://www.twitter.com/fs_Aur http://www.aavso.org Description: FS Aur is one of the most strangest and erratic variable Stars. Peter Lake reports on the data collected as part of the broader work with Dr Vitaly Neustroev of the Oulu University Finland and discusses the past two seasons of observations. Peter Lake is an Amateur Astronomer from Melbourne Australia and regularly discusses how people can be involved in citizen science and observation programs. Bio: Peter Lake is an amateur Astronomer from Melbourne, Australia, a member of Variable Stars South and the AAVSO and he owns and operates a 0.5m Planewave CDK Telescope at New Mexico skies, which is affiliated to iTelescope.net. Peter has been a participant in citizen science and recovered asteroid 2000 EV70 during the Spacewatch FMO program. More recently Peter has been actively involved in the study of cataclysmic variable star FS Aur, and followup exoplanet observations on Kepler targets of interest. Sponsor: "This episode of 365 days of astronomy is sponsored with thanks to all non-US contributors for showing us that the night sky is something we can all share." "Additional sponsorship for this episode of 365 days of astronomy was provided by iTelescope.net - Expanding your horizons in astronomy today. The premier on-demand telescope network, at dark sky sites in Spain, New Mexico and Siding Spring, Australia." Transcript: Like duck hunting, Variable Stars have their "Seasons" also. A season being where the variable star in question is in the optimal position for "shooting with CCDs" ie observable for most of the night, during this time ideally it can be visible for as many as 6-7 hours per night. FS Aur is a Cataclysmic Variable is now low in the west at sunset at the close of an intensive second season. So I though it would be good to review these past two seasons, before once again, it comes around for observations in the next northern winter. FS Aur is one of the strangest and complex objects in the extensive variable star family. It is thought to be a magnetic white dwarf and red giant binary Star with a third object acting on it in a circumbinary orbit. (Tovmassian et al., 2010) Back in 2010 there was a sporadic and incomplete light curve and astronomers wanted answers. When they want answers they often leverage the collective effort of the American Association of Variable Star Observers (AAVSO), to muscle up some more observations and data. FS Aur has a number of photometric and spectroscopic cycles going on. On top of this it goes into outburst about every 12-15 days. The outburst duration is so short (2-3 days) it has been regularly missed in the past - so in the 2010/11 season Dr Neustroev rallied a special effort. For the first time, members of the AAVSO mapped the entire outburst cycle, a good number of times. Dr Vitaly Neustroev is the University Researcher (Yliopistotutkija) at the University of Oulu, Finland and he is a key researcher on FS Aur, working hard to better understand its erratic behaviour. Visit the observing campaign page here, and also follow on (Twitter). I like following Cataclysmic Variables, after catching Simostronomy fever, and I have been a regular on FS Aur since Dr Neustroev's call to action. During the campaign FS Aur has been dancing away with a little periodic wobble at about 15.9 with the odd subtle change in brightness, then it goes really dull to 16.2 then literally within 24-36 hours it pops up to magnitude about Mag 14. As an amateur astronomer I am always careful to point out that I'm not qualified to say how or why, but I can tell you when, where and how bright! So what is going on with FS Aur - Dr Neustroev describes it this way: 365 Days of Astronomy no May 9th: Astronomy Word of the Week: Nova http://365daysofastronomy.org/2012/05/09/may-9th-astronomy-word-of-the-week-nova/ http://365daysofastronomy.org/2012/05/09/may-9th-astronomy-word-of-the-week-nova/#comments Wed, 09 May 2012 11:00:09 +0000 kortney.hogan http://365daysofastronomy.org/?p=7650 Date: May 9, 2012 Title: Astronomy Word of the Week: Nova Podcaster: Dr. Christopher Crockett Organization: United States Naval Observatory Links: http://christophercrockett.com http://astrowow.wordpress.com/ Description: Why do once invisible stars suddenly flare up and then slowly fade from view? The astronomy word of the week is "nova". Bio: Dr. Christopher Crockett is an astronomer at the United States Naval Observatory in Flagstaff, Arizona. His research involves searching for planets around very young stars (“only” a few million years old). It is hoped that the results from this research will help constrain models of planet formation and lead to a better understanding of where, when, and how often planets form. Chris is also passionate about astronomy outreach and education and will talk for hours about the Universe if you let him. Sponsors: Sponsorship for this episode of "365 days of Astronomy" is donated anonymously and dedicated to the men and women of NASA who strive to turn science fiction into science reality. Additional sponsorship for this episode has been provided by iTelescope.net - Expanding your horizons in astronomy today. The premier on-demand telescope network, at dark sky sites in Spain, New Mexico and Siding Spring, Australia. Transcript: In 1572, Danish astronomer Tycho Brahe, along with observers around the world, noticed a new star in the constellation Casseiopeia. Rivaling Venus as the brightest object in the night sky after the Moon, the unexpected guest remained visible for nearly two years before fading from view. The appearance of a new star was nothing short of revolutionary; astronomers long agreed that the celestial sphere was unchanging. A transient star challenged this assumption and suggested that the heavens were perhaps more dynamic than originally thought. The celestial intruder came to be known as a "nova" - after Tycho Brahe's extensive manuscript on the phenomenon - where he referred to the object simply by the latin term for a new star: "stella nova". While no one could have known it at the time, the new star was actually not new at all but rather a very old star experiencing a cataclysmic event. Most of the stars in the sky are not singular, like our Sun, but rather members of binary star systems - two stars locked in orbit around one another. Of this pair, one star is often more massive than its companion and therefore burns through its nuclear fuel at a faster rate. The heavier star reaches the end of its life before its sibling. When it does, the star inflates to become a red giant and sheds its outer layers into space leaving behind the hot, dense stellar core. The naked core, known as a "white dwarf", continues to orbit its stellar neighbor while taking the next few billion years to passively cool from a white-hot 100,000 degrees. In the case of close binary pairs, the white dwarf can actually siphon matter off of its companion. The intermingled gravitational fields of the two stars builds a bridge of predominately hydrogen gas spanning the distance between them. Gas from the still active star flows through this gravitational funnel and spills on to the surface of the white dwarf. The mass of the white dwarf controls the rate of mass accretion; if the rate is high enough, then something quite spectacular can happen. White dwarfs are an example of a rather exotic type of matter that physicists call "degenerate". Most gasses expand when you heat them up: the increasing temperature causes the molecules to zip around faster which in turn increases the gas pressure. At extreme densities - like those seen in the cores of stars - the gas behaves rather peculiarly. The pressure is no longer a slave to temperature: turn up the heat and the gas does not expand. This counterintuitive behavior is crucial to what happens next on the white dwarf's surface. As hydrogen from the donor star comes crashing down, the crushing force of gravity compresses it into a degenerate state and the intense radiation heats the gas to many millions of degrees. But having now obtained the properties of a degenerate gas, the newly acquired hydrogen shell doesn't expand in response to the rapid heating, but holds its pressure steady. And now things get interesting. At temperatures exceeding 16 million degrees Celsius, conditions on the surface mimic those deep in the cores of stars and a thermonuclear explosion is the result. Hydrogen is rapidly fused into helium and the resulting release of energy blows the outer hydrogen shell off the surface of the white dwarf at speeds exceeding ten million kilometers per hour. In mere days, the white dwarf can increase its brightness by 100,000 times. It can then take months - or in some cases years - for the star to slowly fade from view. Our Milky Way Galaxy experiences several dozen novae each year, only about ten of which are visible from Earth. A few are even visible to the naked eye. The most recent nova to be seen without the aid of binoculars or telescopes did so in the constellation Scorpius, reaching its peak brightness on February 17, 2007. Even more rare are what astronomers call "recurrent nova". Once the white dwarf has blown the hydrogen shell into space, the gas can slowly start building up again. These are novae that flare up repeatedly, sometimes once a year, sometimes once every couple of decades. In our whole galaxy, only ten novae are known to be recurrent. In the centuries since the new star of 1572, astronomers have come to realize that the event which gave novae their name was not what we know now as a nova. Up until early in the 20th century, a nova referred to any rapid brightening of a star. But there are many reasons stars suddenly flare into view. What Tycho saw was actually something far more powerful - a type of, aptly named, supernova. The supernova of 1572 was not the result of a flash of hydrogen burning on a white dwarf shell, but rather was caused by the complete detonation of a white dwarf. By stealing gas from a nearby companion slowly enough, the progenitor of the supernova delayed a nova flash while gradually increasing its temperature and pressure and eventually igniting hydrogen fusion throughout the interior of the once dead stellar core. With out the counterbalancing force of the rest of the star to throttle these reactions, the now violently active core obliterated itself in one of the most powerful explosions the Universe can produce. The event of 1572 ushered in a new era of astronomy, one in which the constancy of the celestial sphere could no longer be assumed. Novae - and their more powerful supernovae cousins - are constant reminders that we, in fact, live in a highly dynamic and energetic Universe. End of podcast: 365 Days of Astronomy ===================== The 365 Days of Astronomy Podcast is produced by the Astrosphere New Media Association. Audio post-production by Preston Gibson. Bandwidth donated by libsyn.com and wizzard media. Web design by Clockwork Active Media Systems. You may reproduce and distribute this audio for non-commercial purposes. Please consider supporting the podcast with a few dollars (or Euros!). Visit us on the web at 365DaysOfAstronomy.org or email us at info@365DaysOfAstronomy.org. Until tomorrow...goodbye.]]> http://365daysofastronomy.org/2012/05/09/may-9th-astronomy-word-of-the-week-nova/feed/ 0 podcast iya 365 Date: May 9, 2012 - Title: Astronomy Word of the Week: Nova - Podcaster: Dr. Christopher Crockett - Organization: United States Naval Observatory - Links: http://christophercrockett.com http://astrowow.wordpress.com/ - Date: May 9, 2012 Title: Astronomy Word of the Week: Nova Podcaster: Dr. Christopher Crockett Organization: United States Naval Observatory Links: http://christophercrockett.com http://astrowow.wordpress.com/ Description: Why do once invisible stars suddenly flare up and then slowly fade from view? The astronomy word of the week is "nova". Bio: Dr. Christopher Crockett is an astronomer at the United States Naval Observatory in Flagstaff, Arizona. His research involves searching for planets around very young stars (“only” a few million years old). It is hoped that the results from this research will help constrain models of planet formation and lead to a better understanding of where, when, and how often planets form. Chris is also passionate about astronomy outreach and education and will talk for hours about the Universe if you let him. Sponsors: Sponsorship for this episode of "365 days of Astronomy" is donated anonymously and dedicated to the men and women of NASA who strive to turn science fiction into science reality. Additional sponsorship for this episode has been provided by iTelescope.net - Expanding your horizons in astronomy today. The premier on-demand telescope network, at dark sky sites in Spain, New Mexico and Siding Spring, Australia. Transcript: In 1572, Danish astronomer Tycho Brahe, along with observers around the world, noticed a new star in the constellation Casseiopeia. Rivaling Venus as the brightest object in the night sky after the Moon, the unexpected guest remained visible for nearly two years before fading from view. The appearance of a new star was nothing short of revolutionary; astronomers long agreed that the celestial sphere was unchanging. A transient star challenged this assumption and suggested that the heavens were perhaps more dynamic than originally thought. The celestial intruder came to be known as a "nova" - after Tycho Brahe's extensive manuscript on the phenomenon - where he referred to the object simply by the latin term for a new star: "stella nova". While no one could have known it at the time, the new star was actually not new at all but rather a very old star experiencing a cataclysmic event. Most of the stars in the sky are not singular, like our Sun, but rather members of binary star systems - two stars locked in orbit around one another. Of this pair, one star is often more massive than its companion and therefore burns through its nuclear fuel at a faster rate. The heavier star reaches the end of its life before its sibling. When it does, the star inflates to become a red giant and sheds its outer layers into space leaving behind the hot, dense stellar core. The naked core, known as a "white dwarf", continues to orbit its stellar neighbor while taking the next few billion years to passively cool from a white-hot 100,000 degrees. In the case of close binary pairs, the white dwarf can actually siphon matter off of its companion. The intermingled gravitational fields of the two stars builds a bridge of predominately hydrogen gas spanning the distance between them. Gas from the still active star flows through this gravitational funnel and spills on to the surface of the white dwarf. The mass of the white dwarf controls the rate of mass accretion; if the rate is high enough, then something quite spectacular can happen. White dwarfs are an example of a rather exotic type of matter that physicists call "degenerate". Most gasses expand when you heat them up: the increasing temperature causes the molecules to zip around faster which in turn increases the gas pressure. At extreme densities - like those seen in the cores of stars - the gas behaves rather peculiarly. The pressure is no longer a slave to temperature: turn up the heat and the gas does not expand. This counterintuitive behavior is crucial to what happens next on the white dwarf's surface. As hydrogen from the donor star comes crashing down, 365 Days of Astronomy no May 8th: What is Black http://365daysofastronomy.org/2012/05/08/may-8th-what-is-black/ http://365daysofastronomy.org/2012/05/08/may-8th-what-is-black/#comments Tue, 08 May 2012 11:00:41 +0000 kortney.hogan http://365daysofastronomy.org/?p=7646 Date: May 8, 2012 Title: What is Black Podcaster: Rob Sparks & Dr. Steven Pompea Organization: NOAO Links: www.noao.edu Description: Most people think of black as a color, but black is really the absence of light. Truly black surfaces reflect almost none of the light that falls on them. In this podcast, Dr. Stephen Pompea discusses black surface, how they are produced and why they are important in astronomy and other sciences. Bio: Rob Sparks is a science education specialist in the EPO group at NOAO and works on the Galileoscope project (www.galileoscope.org), providing design, dissemination and professional development. He also pens a great blog at halfastro.wordpress.com. Dr. Stephen Pompea did his undergraduate work in physics, space physics, and astronomy at Rice University, his Master’s work in physics teaching at Colorado State University, and his Ph.D. in astronomy at the University of Arizona. He is currently the manager of the Education and Public Outreach Group at the National Optical Astronomy Observatory. Sponsor: This episode of the 365 Days of Astronomy podcast is sponsored by the National Optical Astronomy Observatory. NOAO is a US national research and development center for ground-based nighttime astronomy. We provide astronomers access to world-class observing facilities on a peer-reviewed basis. Our mission is to engage in programs to develop the next generation of telescopes, instruments, and software tools necessary to enable exploration and investigation through the observable Universe. For information on observing proposals or our public programs, please visit www.noao.edu for more information. "This episode has also been sponsored by the Lake County Astronomical Society: Celebrating 30 years of stellar service to members and the public." Transcript: *** Transcript coming soon. *** End of podcast: 365 Days of Astronomy ===================== The 365 Days of Astronomy Podcast is produced by the Astrosphere New Media Association. Audio post-production by Preston Gibson. Bandwidth donated by libsyn.com and wizzard media. Web design by Clockwork Active Media Systems. You may reproduce and distribute this audio for non-commercial purposes. Please consider supporting the podcast with a few dollars (or Euros!). Visit us on the web at 365DaysOfAstronomy.org or email us at info@365DaysOfAstronomy.org. Until tomorrow...goodbye.]]> http://365daysofastronomy.org/2012/05/08/may-8th-what-is-black/feed/ 0 podcast iya 365 Date: May 8, 2012 - Title: What is Black - Podcaster: Rob Sparks & Dr. Steven Pompea - Organization: NOAO - Links: www.noao.edu - Description: Most people think of black as a color, but black is really the absence of light. Date: May 8, 2012 Title: What is Black Podcaster: Rob Sparks & Dr. Steven Pompea Organization: NOAO Links: www.noao.edu Description: Most people think of black as a color, but black is really the absence of light. Truly black surfaces reflect almost none of the light that falls on them. In this podcast, Dr. Stephen Pompea discusses black surface, how they are produced and why they are important in astronomy and other sciences. Bio: Rob Sparks is a science education specialist in the EPO group at NOAO and works on the Galileoscope project (www.galileoscope.org), providing design, dissemination and professional development. He also pens a great blog at halfastro.wordpress.com. Dr. Stephen Pompea did his undergraduate work in physics, space physics, and astronomy at Rice University, his Master’s work in physics teaching at Colorado State University, and his Ph.D. in astronomy at the University of Arizona. He is currently the manager of the Education and Public Outreach Group at the National Optical Astronomy Observatory. Sponsor: This episode of the 365 Days of Astronomy podcast is sponsored by the National Optical Astronomy Observatory. NOAO is a US national research and development center for ground-based nighttime astronomy. We provide astronomers access to world-class observing facilities on a peer-reviewed basis. Our mission is to engage in programs to develop the next generation of telescopes, instruments, and software tools necessary to enable exploration and investigation through the observable Universe. For information on observing proposals or our public programs, please visit www.noao.edu for more information. "This episode has also been sponsored by the Lake County Astronomical Society: Celebrating 30 years of stellar service to members and the public." Transcript: *** Transcript coming soon. *** End of podcast: 365 Days of Astronomy ===================== The 365 Days of Astronomy Podcast is produced by the Astrosphere New Media Association. Audio post-production by Preston Gibson. Bandwidth donated by libsyn.com and wizzard media. Web design by Clockwork Active Media Systems. You may reproduce and distribute this audio for non-commercial purposes. Please consider supporting the podcast with a few dollars (or Euros!). Visit us on the web at 365DaysOfAstronomy.org or email us at info@365DaysOfAstronomy.org. Until tomorrow...goodbye. 365 Days of Astronomy no May 7th: The Late Heavy Bombardment — an Extended Version? http://365daysofastronomy.org/2012/05/13/may-13th-encore-exploring-space-from-space/ http://365daysofastronomy.org/2012/05/13/may-13th-encore-exploring-space-from-space/#comments Sun, 13 May 2012 15:04:40 +0000 kortney.hogan http://365daysofastronomy.org/?p=7681 Date: May 13, 2012 Title: Encore: Exploring Space from Space Podcaster: Kenneth Renshaw Links: Solar System Ambassador Website: http://www2.jpl.nasa.gov/ambassador/profiles/Kenneth_Renshaw.htm Saturn Observation Campaign Website: http://soc.jpl.nasa.gov/members-state.cfm?state=AR This podcast originally aired on April 12th, 2009 http://365daysofastronomy.org/2009/04/12/april-12th-exploring-space-from-space/ Description: Kenneth Renshaw is a college music instructor, piano teacher/tuner/technician, church choir director/pianist, photographer and videographer from the small town of Piggott, Arkansas. He graduated from Southern Baptist College and Arkansas State University with Associate, Bachelor, and Masters degrees in music education, but has had the hobby of amateur astronomy since before the age of 16. He is a Solar System Ambassador and a member of the Saturn Observation Campaign for NASA’s Jet Propulsion Laboratory and does space presentations for numerous schools and organizations. He is married to Rachel Burden, with 2 stepdaughters, Melody, 16, and Liberty, 15. Bio: Almost since the beginning of the space age, NASA and the other space programs have used spacecraft to actively research astronomy, from our solar system to the furthest reaches of the universe. This podcast is a brief summary of the current spacecraft being used to explore astronomy-from the nearby Moon to the edge of the observable universe, the Cosmic Background Radiation. Today's Sponsor: This episode of 365 days of astronomy was sponsored by iTelescope.net - Expanding your horizons in astronomy today. The premier on-demand telescope network, at dark sky sites in Spain, New Mexico and Siding Spring, Australia. Transcript: Welcome to the podcast: Exploring Space from Space. I’m Kenneth Renshaw, a member of the Saturn Observation Campaign and a Solar System Ambassador for NASA. Almost since the beginning of the space age, NASA and the other space programs have used spacecraft to actively research astronomy, from our solar system to the furthest reaches of the universe. This podcast is a brief summary of the current spacecraft being used to explore astronomy-from the nearby Moon to the edge of the observable universe, the Cosmic Background Radiation. To stay within reasonable time limits, we will focus on spacecraft used for astronomy, rather than the hundreds of satellites used to study the earth. First, the nearest star, our Sun. For obvious reasons (the heat), satellites that study the Sun are usually in a distant orbit around it, such as at the Earth’s distance. There are many probes studying the Sun and its effect on the Earth. Ulysses is a spacecraft that orbits the Sun in a polar orbit, giving us the first look at the polar regions of the Sun. SOHO, the Solar and Heliospheric Observatory, is a joint effort of NASA and the European Space Agency, launched in December 1995 to an area beyond Earth’s orbit. It has 3 instruments that can monitor the interior of the Sun in a science called helioseismology. The FAST, a low altitude mission around the Earth, and POLAR, at a high altitude, are used together to study the particles, charge, and magnetism in the ionosphere and how they affect the Oxygen in Earth’s atmosphere. Launched in 1997, ACE studies the solar wind from a Lagrange point between the Earth and the Sun. In 2000, the European Space Agency launched CLUSTER, a set of 4 spacecraft in Earth orbit, studying the interaction of the solar wind and the magnetosphere, particularly the magnetic reconnection events that cause solar storms. The 2000 launch of IMAGE began the imaging of the plasmas above the Earth, with far and extreme ultraviolet, neutral atom imaging, and radio sounding. It is in a highly elliptical orbit around the Earth. TWINS, or Two Wide-angle Imaging Neutral-atom Spectrometers, are 2 spacecraft in a high orbit of the Earth, giving a 3-D view of the magnetosphere. THEMIS, a 2 year mission using 5 identical orbiters, is studying the auroras in improving our predictions of Space Weather., Solar-B or Hinode is a Japanese, United Kingdom, and NASA collaboration in a sun-synchronous polar orbit, launched in 2006. It studies the sun in high resolution visual, ultraviolet, and X-Ray wavelengths. The 2006 mission, STEREO, or Solar Terrestrial Relations Observatory, consists of 2 spacecraft positioned one ahead and one behind Earth’s orbit, providing a stereoscopic view of solar activity, enabling more accurate predictions of when that activity will affect Earth, as well as one of the probes showing us the activity on the hidden side of the Sun before it rotates around to our side, also enabling better forecasting. The Advanced Composition Explorer, or ACE, is at a Lagrange Point between the Earth and Sun, studying solar, as well as interstellar particles. Earlier this year, the IBEX, or Interstellar Boundary Explorer, was launched in a high orbit 2/3 of the way to the Moon. It collects particles from the boundary of the Sun’s influence, far beyond Pluto. It will study what is known as the Termination Shock, where interstellar wind begins to mix with the Solar wind. Planetary probes are spacecraft that actually visit these worlds, sometimes landing on them. Starting at the first planet, Mercury, the first spacecraft designed to orbit the planet is on its was to the hot, airless world near the Sun after a 2004 launch. Messenger—the Mercury Surface, Space Environment, Geochemistry, and Ranging Mission—has made 2 flybys of Mercury so far, and, after another flyby in September of this year, will go into orbit on March 18, 2011. It will make a comprehensive study of Mercury for 1 year. At the cloud-enshrouded, and therefore, hottest planet, with a runaway greenhouse effect, the Venus Express was placed into orbit around the second planet in April 2006 by ESA, the European Space Agency. Among its many instruments is the ability to monitor Venus from the thermal infrared to the ultraviolet wavelengths. At the Moon, the SELENE (also known as Kaguya) is in orbit, sent by JAXA, the Japanese Space Agency, as is Chandrayaan 1, a project of India. To be launched in early June is NASA’s Lunar Reconnaissance Orbiter along with an impactor, LCROSS. Colliding into a permanently shaded crater at one of the Moon’s poles, the LCROSS should kick up a plume of vapor from the theorized water ice in the crater, giving astronauts a source of water and fuel for a future lunar base. At Mars are 3 spacecraft on the surface--a lander that recently completed its mission at the north polar region, Phoenix, and the rovers, Spirit and Opportunity. The 2 rovers were planned for a 90 day mission in 2004, but have been extremely successful over the past 5 years—20 times the expected time, a surprise for everyone. Next roving on the surface will be the Mars Science Laboratory, to be launched in 2011. In orbit around Mars is NASA’s Mars Odyssey and the high-resolution cameras of the Mars Reconnaissance Orbiter, as well as Europe’s Mars Express. On its way to orbit not one, but 2 objects in the asteroid belt, is Dawn. It will orbit the asteroid Vesta, and the former asteroid promoted to a dwarf planet, Ceres. It will then be the first spacecraft in history to orbit 2 objects. No spacecraft is currently around Jupiter, after the conclusion of the Galileo mission, that plunged through the crushing atmosphere of Jupiter in September 2003. However, the New Horizons recently flew by and studied Jupiter, as well as steal a microscopic bit of Jupiter’s orbital momentum to give it a boost to its destination of Pluto. At Saturn is the highly successful orbiter, Cassini, now in a two-year extension of an original 4-year mission. It has studied Saturn, its rings, its magnetospheric environment, and its moons. In January 2005, an attached lander, Huygens, landed on the haze enshrouded moon, Titan. Titan is the only moon in the Solar System that has a thick atmosphere, and is a cold version of the biochemistry of early Earth. No probes since Voyager 2 have visited Uranus or Neptune. On its way to Pluto is the New Horizons. Coincidentally, on my 20th wedding anniversary on July 14, 2015, New Horizons will fly by Pluto and its 3 moons, and then go on to fly by a yet determined destination in the Kuiper belt. When Deep Impact hit Comet Tempel 1 on the 4th of July of 2005, it left a crater that, unfortunately, was too enshrouded in a dust plume to be observed. The Stardust spacecraft, that collected comet particles from Wild 2, is now on it way to Tempel 1 to check the remains of this collision. Meanwhile, Deep Impact is now called Epoxi, and is now studying extrasolar planets that transit their stars, and will also fly by Comet Hartley next year. This is getting 2 for the price of one, using these 2 spacecraft. We have now toured the main objects of the Solar System. Let now go back to Earth, where a number of spacecraft are orbiting, and studying things far beyond the Sun’s domain, even to the very edge of the observable universe. Telescopes and other instruments are placed in orbit, since our atmosphere blurs and can actually block much of the electromagnetic radiation we need to study to get a complete picture of the universe. In visible light and the near ultraviolet and infrared we have the Hubble Space Telescope; in the infrared, we have the Spitzer Space Telescope. SOFIA is an infrared telescope onboard an aircraft. GALEX, or Galaxy Evolution Explorer, is an ultraviolet probe, photographing millions of galaxies in the UV since 2003. To pick up the X-Ray, we have Chandra, the Japanese/US collaboration, Suzaku, and Europe’s XMM-Newton. RXTE, the Rossi X-Ray Timing Explorer studies black holes, neutron stars, X-Ray Pulsars, and X-Ray bursts in this frequency. CHIPS, or the Cosmic Hot Interstellar Plasma Spectrometer is monitoring the plasma in our galaxy. Last month, Kepler was launched to constantly monitor the light output of 100,000 stars and detect any planets passing in front of their star, and try to find out what percentage of stars have planets in the habitable zone. The Fermi spacecraft (formerly called GLAST for Gamma Ray Large Area Space Telescope) monitors the sky for Gamma Ray Bursts, and also has a telescope to study this high-energy radiation. On the other hand, the Swift spacecraft studies bursts in Gamma Rays, X Rays, UV, and Optical wavelengths. HETE-2 has, for over 6 years, also been used to detect these most massive explosions in the universe. Integral is a gamma ray spectrometer launched by the European Space Agency. And lastly, WMAP, the Wilkinson Microwave Anisotropy Probe, has, in high resolution, mapped the Cosmic Background Radiation and determined the universe to be 13.73 billion years old, +/- 1%. Thanks for joining us for a more clear view of the universe, thanks to the space age, and thanks for listening to 365 Days of Astronomy. End of podcast: 365 Days of Astronomy ===================== The 365 Days of Astronomy Podcast is produced by the New Media Working Group of the International Year of Astronomy 2009. Audio post-production by Preston Gibson. Bandwidth donated by libsyn.com and wizzard media. Web design by Clockwork Active Media Systems. You may reproduce and distribute this audio for non-commercial purposes. Please consider supporting the podcast with a few dollars (or Euros!). Visit us on the web at 365DaysOfAstronomy.org or email us at info@365DaysOfAstronomy.org. Until tomorrow...goodbye.]]> http://365daysofastronomy.org/2012/05/13/may-13th-encore-exploring-space-from-space/feed/ 0 podcast iya 365 Date: May 13, 2012 - Title: Encore: Exploring Space from Space - Podcaster: Kenneth Renshaw - Links: Solar System Ambassador Website: http://www2.jpl.nasa.gov/ambassador/profiles/Kenneth_Renshaw.htm Saturn Observation Campaign Website: Date: May 13, 2012 Title: Encore: Exploring Space from Space Podcaster: Kenneth Renshaw Links: Solar System Ambassador Website: http://www2.jpl.nasa.gov/ambassador/profiles/Kenneth_Renshaw.htm Saturn Observation Campaign Website: http://soc.jpl.nasa.gov/members-state.cfm?state=AR This podcast originally aired on April 12th, 2009 http://365daysofastronomy.org/2009/04/12/april-12th-exploring-space-from-space/ Description: Kenneth Renshaw is a college music instructor, piano teacher/tuner/technician, church choir director/pianist, photographer and videographer from the small town of Piggott, Arkansas. He graduated from Southern Baptist College and Arkansas State University with Associate, Bachelor, and Masters degrees in music education, but has had the hobby of amateur astronomy since before the age of 16. He is a Solar System Ambassador and a member of the Saturn Observation Campaign for NASA’s Jet Propulsion Laboratory and does space presentations for numerous schools and organizations. He is married to Rachel Burden, with 2 stepdaughters, Melody, 16, and Liberty, 15. Bio: Almost since the beginning of the space age, NASA and the other space programs have used spacecraft to actively research astronomy, from our solar system to the furthest reaches of the universe. This podcast is a brief summary of the current spacecraft being used to explore astronomy-from the nearby Moon to the edge of the observable universe, the Cosmic Background Radiation. Today's Sponsor: This episode of 365 days of astronomy was sponsored by iTelescope.net - Expanding your horizons in astronomy today. The premier on-demand telescope network, at dark sky sites in Spain, New Mexico and Siding Spring, Australia. Transcript: Welcome to the podcast: Exploring Space from Space. I’m Kenneth Renshaw, a member of the Saturn Observation Campaign and a Solar System Ambassador for NASA. Almost since the beginning of the space age, NASA and the other space programs have used spacecraft to actively research astronomy, from our solar system to the furthest reaches of the universe. This podcast is a brief summary of the current spacecraft being used to explore astronomy-from the nearby Moon to the edge of the observable universe, the Cosmic Background Radiation. To stay within reasonable time limits, we will focus on spacecraft used for astronomy, rather than the hundreds of satellites used to study the earth. First, the nearest star, our Sun. For obvious reasons (the heat), satellites that study the Sun are usually in a distant orbit around it, such as at the Earth’s distance. There are many probes studying the Sun and its effect on the Earth. Ulysses is a spacecraft that orbits the Sun in a polar orbit, giving us the first look at the polar regions of the Sun. SOHO, the Solar and Heliospheric Observatory, is a joint effort of NASA and the European Space Agency, launched in December 1995 to an area beyond Earth’s orbit. It has 3 instruments that can monitor the interior of the Sun in a science called helioseismology. The FAST, a low altitude mission around the Earth, and POLAR, at a high altitude, are used together to study the particles, charge, and magnetism in the ionosphere and how they affect the Oxygen in Earth’s atmosphere. Launched in 1997, ACE studies the solar wind from a Lagrange point between the Earth and the Sun. In 2000, the European Space Agency launched CLUSTER, a set of 4 spacecraft in Earth orbit, studying the interaction of the solar wind and the magnetosphere, particularly the magnetic reconnection events that cause solar storms. The 2000 launch of IMAGE began the imaging of the plasmas above the Earth, with far and extreme ultraviolet, neutral atom imaging, and radio sounding. It is in a highly elliptical orbit around the Earth. TWINS, or Two Wide-angle Imaging Neutral-atom Spectrometers, are 2 spacecraft in a high orbit of the Earth, giving a 3-D view of the magnetosphere. 365 Days of Astronomy no 365 Days of Astronomy http://365daysofastronomy.org An astronomy podcast every day, all year Wed, 16 May 2012 11:00:41 +0000 en hourly 1 http://wordpress.org/?v=3.1 An astronomy podcast every day, all year 365 Days of Astronomy no An astronomy podcast every day, all year 365 Days of Astronomy http://365daysofastronomy.org/wp-content/plugins/powerpress/rss_default.jpg http://365daysofastronomy.org May 16th: GPS http://365daysofastronomy.org/2012/05/16/may-16th-gps/ http://365daysofastronomy.org/2012/05/16/may-16th-gps/#comments Wed, 16 May 2012 11:00:41 +0000 kortney.hogan http://365daysofastronomy.org/?p=7689 Date: May 16, 2012 Title: GPS Podcaster: Steve Nerlich Organization: Cheap Astronomy Links: www.cheapastro.com Description: Cheap Astronomy once again demonstrates that pretty much everything in life has a connection to astronomy. Bio: Cheap Astronomy offers an educational website because in space no-one can hear you podcast. Today's Sponsor: "This episode of 365 days of Astronomy" is sponsored by the Lake County Astronomical Society: Celebrating 30 years of stellar service to members and the public." Additional sponsorship for this episode has also been provided by iTelescope.net - Expanding your horizons in astronomy today. The premier on-demand telescope network, at dark sky sites in Spain, New Mexico and Siding Spring, Australia. Transcript: Hi this is Steve Nerlich from Cheap Astronomy www.cheapastro.com and this is GPS OK – If you don’t have one, you know someone who does, so let’s skip the introductions and get straight down to the astronomy. A standard GPS configuration is a constellation of 24 GPS satellites. The satellites are all at an altitude of 20,200 km with an orbital period of 11 hours and 58 minutes – which means they do exactly 2 orbits for each time the Earth spins once on its axis. Four satellites each follow six orbital planes separated by 60 degrees which surround the Earth in an (airquotes) ‘birdcage’ of criss-crossing orbits. There a link to the relevant Wikipedia article from the Cheap Astronomy podcast page which has a nice animation of a GPS satellite constellation. At last count, there were actually 31 actively transmitting GPS satellites – with these extra number increasing location accuracy and redundancy. There’s been some recent media regarding a growing risk of dropping below the minimum 24 active satellites required to make GPS work effectively, but it remains to be seen if this risk will be realised in the face of the increasing economic importance of maintaining a working GPS system. A GPS satellite broadcasts a signal indicating where it is and the time the signal was broadcast – your receiver then determines, from the time it receives that signal, the distance travelled by the signal, knowing that, being a radio transmission, the signal travels at the speed of light. By making just four calculations from four satellites in the sky, your GPS receiver can then establish its position with respect to latitude, longitude and altitude. It’s all about the conjunction of spheres. Imagine one satellite broadcasting a radio signal. If you pick up that signal and determine it’s a 100 km away, all you really know is that you are somewhere on a surface of a sphere with a 100 km radius that has the satellite at its centre. If there’s two such satellites then you’ll know you are somewhere on the circumference of a circle representing the plane where the two spheres of radio broadcast overlap. Introduce a third satellite and you can narrow down your location to just two points in space which are the points where two differently orientated circle circumferences intersect. Potentially this may be enough to roughly determine your position since you can anticipate you will be on the one of those two points corresponding to the surface of the Earth. But for strictest accuracy – including accuracy in determining your altitude above sea level, the signal from a fourth satellite is required. And that is the idea of the constellation of GPS satellites. Keeping 24 satellites moving in the same orbit, tracing a birdcage of divergent paths around the globe ensures there will always be four satellites in the sky wherever you happen to be on Earth. Now when I say GPS satellites just have to broadcast where they are – actually knowing where they are is a whole separate operation, While the orbital period is predictable, knowing at what point they are on that orbit requires some very accurate time keeping – for which reason each satellite has an atomic clock. Nonetheless, even this isn’t enough, as the orbital paths of the satellites are subject to slight shifting due to the gravitational influence of the Sun and the Moon. To keep track of these changes the satellites are monitored from a fixed, known location on the Earth’s surface – a function currently managed by the 50th Space Wing of the US Airforce Space Command – seriously. Now, given that your GPS receiver is working out its distance from each of four satellites based solely on the time lag of a signal moving at the speed of light from a satellite just over 20,000 kilometres away – there is considerable potential for a margin of error that could see you driving over the embankment into a river when that sexy voice says ‘turn left now’. There are a range of methods to deal with various sources of error. Firstly your GPS receiver carries an electronic almanac of which satellite should be where since confusion can arise when the satellite radio signals get reflected off surroundings, such as tall buildings. This electronic almanac is constructed from calibration data received from the GPS satellites, although these data are generally relayed from a ground-based source – such as Airforce Space Command. The almanac helps your receiver distinguish between garbage signals and genuine GPS signals. The receiver also receives time checks from the satellites since, most GPS receivers determine time from a cheap (not that there’s anything wrong with that) quartz clock rather than the ultra-accurate atomic clocks of the satellites. Clock error is probably the biggest potential source of GPS error, which is why, even though you could almost get away with determining your position from just 3 satellites, it is the fourth reading (which we might call quadrangulation) that ensures the poorer accuracy of the GPS receiver’s clock is effectively accounted for. Interestingly, there’s also relativistic effects to account for, since the satellites move in a weaker gravity field (meaning by general relativity their clocks run faster), and they also move at speed relative to the surface of the Earth (meaning by special relativity their clocks run slower). It turns out that the nett effect is that the satellites’ clocks run about 38 microseconds per day faster than they would at the Earth’s surface. To account for this, the clocks are actually set to run at a slightly lower rate, to keep pace with clocks running on the Earth’s surface. In the world of atomic clocks, various time keeping callibrations are also required to account for changes in the rotation of the Earth – which is influenced by the tidal drag of the Moon , the inertia of the Earth’s molten interior and even the melting of glaciers. Overall, the Earth’s rotation is slowing, leading to a lengthening of a solar day. Consequently a leap second must be introduced to atomic timepieces which measure Universal Coordinated Time (known as UTC – because of the French). In fact, a leap second is required to be added to UTC every 18 months or so because each year (on average) the length of a solar day increases by about 0.002 seconds. The atomic clocks of GPS satellites were aligned to UTC in 1980 – but as of 2009, these atomic clocks in orbit now vary by 19 seconds and to keep it simple we just say they are running at GPS time. Various under-the-hood adjustments are made along the way so that your GPS receiver can tell you the local time wherever you happen to be – as well as telling you where you are of course to within… well, within 10 metres is the general benchmark, although this takes a few minutes to establish after the unit is turned on and the accuracy will degrade with tall trees or buildings around. So, you know, it’s a guide – not an absolute – it’s still a good idea to keep one eye on the road. Thanks for listening. This is Steve Nerlich from Cheap Astronomy, www.cheapastro.com. Cheap Astronomy offers an educational website where you can’t put a price on space. No ads, no profit, just good science. Bye. End of podcast: 365 Days of Astronomy ===================== The 365 Days of Astronomy Podcast is produced by the New Media Working Group of the International Year of Astronomy 2009. Audio post-production by Preston Gibson. Bandwidth donated by libsyn.com and wizzard media. Web design by Clockwork Active Media Systems. You may reproduce and distribute this audio for non-commercial purposes. Please consider supporting the podcast with a few dollars (or Euros!). Visit us on the web at 365DaysOfAstronomy.org or email us at info@365DaysOfAstronomy.org. Until tomorrow...goodbye.]]> http://365daysofastronomy.org/2012/05/16/may-16th-gps/feed/ 0 podcast iya 365 Date: May 16, 2012 - Title: GPS Podcaster: Steve Nerlich - Organization: Cheap Astronomy - Links: www.cheapastro.com - Description: Cheap Astronomy once again demonstrates that pretty much everything in life has a connection to astronomy. - Date: May 16, 2012 Title: GPS Podcaster: Steve Nerlich Organization: Cheap Astronomy Links: www.cheapastro.com Description: Cheap Astronomy once again demonstrates that pretty much everything in life has a connection to astronomy. B... 365 Days of Astronomy no May 15th: Astronomy Word of the Week: Obliquity http://365daysofastronomy.org/2012/05/15/may-15th-astronomy-word-of-the-week-obliquity/ http://365daysofastronomy.org/2012/05/15/may-15th-astronomy-word-of-the-week-obliquity/#comments Tue, 15 May 2012 11:00:14 +0000 kortney.hogan http://365daysofastronomy.org/?p=7687 Date: May 15, 2012 Title: Astronomy Word of the Week: Obliquity Podcaster: Dr. Christopher Crockett Organization: United States Naval Observatory Links: http://christophercrockett.com http://astrowow.wordpress.com/ Description: The tilt of our planet is about much more than the seasons. The astronomy word of the week is "obliquity". Bio: Dr. Christopher Crockett is an astronomer at the United States Naval Observatory in Flagstaff, Arizona. His research involves searching for planets around very young stars (“only” a few million years old). It is hoped that the results from this research will help constrain models of planet formation and lead to a better understanding of where, when, and how often planets form. Chris is also passionate about astronomy outreach and education and will talk for hours about the Universe if you let him. Today's Sponsor: "This episode of 365 days of Astronomy" is sponsored by iTelescope.net - Expanding your horizons in astronomy today. The premier on-demand telescope network, at dark sky sites in Spain, New Mexico and Siding Spring, Australia. This episode has also been sponsored by Lake County Astronomical Society: Celebrating 30 years of stellar service to members and the public. Transcript: The planet you're standing on is not very steady. She bobs and wobbles, ducks and weaves, as she makes her annual trek around the Sun. Our home constantly struggles with forces both external and internal; the Sun, the Moon, and the planets tug her back and forth while shifting masses within force her to constantly find new balance. The tilt of our planet's axis - what astronomers call its obliquity - is one measure of this interplanetary tug-of-war. Obliquity measures how far over a planet or moon is tipped relative to its orbit; in the Earth's case, it's about 23 degrees. We feel the obliquity in the changing seasons. In June, the north pole is tipped towards the Sun. The northern hemisphere experiences longer days and more direct sunlight giving us warm summer days. In December, the north pole is tipped away from the Sun and everyone above the equator experiences the bitter chill of winter as the days get shorter and the sunlight reaches us more obliquely. The other planets in our solar system exhibit a wide range of obliquities. Mars, Saturn, and Neptune are all tipped by roughly the same amount as Earth. Mercury and Jupiter have hardly any obliquity at all - which means no seasons for them. Venus' obliquity is 177 degrees; it is almost completely upside down. Put another way, it rotates in the opposite direction from Earth. Were there ever to be a break in Venus' stifling cloud layer, native Venusians would see the Sun rise in the west and set in the east! Uranus is another strange character; his obliquity is 97 degrees. Uranus is lying on his side! This leads to some very strange days and seasons. Each pole of Uranus alternates between being in constant sunlight for 42 years, then perpetual darkness for another 42 years. Only a very thin strip along the equator experiences anything like day/night cycles that we experience - and even then the Sun is frequently sitting very low on the horizon. Astronomers aren't entirely certain how Venus and Uranus came to have such extreme obliquities. A leading hypothesis is that both experienced massive collisions at some point in their distant past, essentially knocking them over. A glancing blow from a minor planet isn't the only thing that can change an obliquity. The tilt of our planet's axis is drifting - ever so slightly - all the time. The poles actually trace out a rather complex dance over time scales ranging from minutes to thousands of centuries. Like a spinning top, our planet also wobbles - though it does so very slowly. Over a period of 26,000 years, the poles trace out a giant circle in the sky. Right now, the north pole points pretty close to the star Polaris. But over time that will change, and in some epochs it will be pointing at nothing at all. This wobble - or precession - doesn't change the amount of obliquity; it simply changes where in space the poles are pointing. The Moon, however, does tug on our planet's axis. In addition to rotation and precession, the Earth experiences something called nutation. This is a slight rocking of the Earth's axis caused by the changing positions of the Moon, the Sun, and all the other bodies in the solar system. With many players involved, the motion from nutation is fairly complex. The main component nods the planet by a couple hundred meters over a nearly 19 year cycle that is tied to how the Moon's orbit drifts around the Earth. Our planet also has to contend with forces much closer to home. Internal motions of magma, deep sea currents, changing ocean salinity, winds, melting ice sheets, and even earthquakes all conspire to constantly change the distribution of mass within the Earth. The planet responds by continuously shifting its spin axis - an effect known as polar motion. This is a bit different than nutation; it actually changes where on Earth the north and south poles are located. Hard as it may be to fathom, these are not fixed locations on the globe. The drift is very small - centimeters per year - but it does add a complex twist to understanding our planets motion in space. The presence of a large moon is believed to help stabilize our obliquity. The tilt does change by a few degrees over many millions of years, but manages to hold steady at around 20-25 degrees. Mars, conversely, appears to be going through a chaotic evolution in its obliquity. Computer simulations of its stability suggest that, over the past few million years, the Red Planet's tilt has oscillated wildly between zero and sixty degrees which may lead to drastic swings in the environment. Many astrobiologists - scientists who study the evolution and origin of life in a cosmic context - argue that our moon may be an essential ingredient for providing a stable environment within which life could thrive. Does this mean that the existence of complex life and advanced civilizations is dependent on the presence of a large satellite? That's hard to say. It is certainly plausible that our closest neighbor in space has been an indispensable partner in the evolution of our species. I'm continually amazed at how a simple concept - like the tilt of a planet - can actually lead down a labyrinthian path of subtleties. Studying Earth's obliquity, and the obliquity of all the other planets and moons, reveals much about the dynamics of our planet, the interplay of our home and neighboring worlds, and even the often times cataclysmic evolution of the solar system. While the subtleties are far removed from our day-to-day lives, our Earth's position in space actually is inseparable from the human experience. The June solstice is just over a month away. Whether you're bundling up for winter, or heading to the beach for summer, remember: the Earth's obliquity is the reason for the seasons! End of podcast: 365 Days of Astronomy ===================== The 365 Days of Astronomy Podcast is produced by the New Media Working Group of the International Year of Astronomy 2009. Audio post-production by Preston Gibson. Bandwidth donated by libsyn.com and wizzard media. Web design by Clockwork Active Media Systems. You may reproduce and distribute this audio for non-commercial purposes. Please consider supporting the podcast with a few dollars (or Euros!). Visit us on the web at 365DaysOfAstronomy.org or email us at info@365DaysOfAstronomy.org. Until tomorrow...goodbye.]]> http://365daysofastronomy.org/2012/05/15/may-15th-astronomy-word-of-the-week-obliquity/feed/ 0 podcast iya 365 Date: May 15, 2012 - Title: Astronomy Word of the Week: Obliquity Podcaster: Dr. Christopher Crockett - Organization: United States Naval Observatory - Links: http://christophercrockett.com http://astrowow.wordpress.com/ - Date: May 15, 2012 Title: Astronomy Word of the Week: Obliquity Podcaster: Dr. Christopher Crockett Organization: United States Naval Observatory Links: http://christophercrockett.com http://astrowow.wordpress.com/ Description: The tilt of our planet is about much more than the seasons. The astronomy word of the week is "obliquity". Bio: Dr. Christopher Crockett is an astronomer at the United States Naval Observatory in Flagstaff, Arizona. His research involves searching for planets around very young stars (“only” a few million years old). It is hoped that the results from this research will help constrain models of planet formation and lead to a better understanding of where, when, and how often planets form. Chris is also passionate about astronomy outreach and education and will talk for hours about the Universe if you let him. Today's Sponsor: "This episode of 365 days of Astronomy" is sponsored by iTelescope.net - Expanding your horizons in astronomy today. The premier on-demand telescope network, at dark sky sites in Spain, New Mexico and Siding Spring, Australia. This episode has also been sponsored by Lake County Astronomical Society: Celebrating 30 years of stellar service to members and the public. Transcript: The planet you're standing on is not very steady. She bobs and wobbles, ducks and weaves, as she makes her annual trek around the Sun. Our home constantly struggles with forces both external and internal; the Sun, the Moon, and the planets tug her back and forth while shifting masses within force her to constantly find new balance. The tilt of our planet's axis - what astronomers call its obliquity - is one measure of this interplanetary tug-of-war. Obliquity measures how far over a planet or moon is tipped relative to its orbit; in the Earth's case, it's about 23 degrees. We feel the obliquity in the changing seasons. In June, the north pole is tipped towards the Sun. The northern hemisphere experiences longer days and more direct sunlight giving us warm summer days. In December, the north pole is tipped away from the Sun and everyone above the equator experiences the bitter chill of winter as the days get shorter and the sunlight reaches us more obliquely. The other planets in our solar system exhibit a wide range of obliquities. Mars, Saturn, and Neptune are all tipped by roughly the same amount as Earth. Mercury and Jupiter have hardly any obliquity at all - which means no seasons for them. Venus' obliquity is 177 degrees; it is almost completely upside down. Put another way, it rotates in the opposite direction from Earth. Were there ever to be a break in Venus' stifling cloud layer, native Venusians would see the Sun rise in the west and set in the east! Uranus is another strange character; his obliquity is 97 degrees. Uranus is lying on his side! This leads to some very strange days and seasons. Each pole of Uranus alternates between being in constant sunlight for 42 years, then perpetual darkness for another 42 years. Only a very thin strip along the equator experiences anything like day/night cycles that we experience - and even then the Sun is frequently sitting very low on the horizon. Astronomers aren't entirely certain how Venus and Uranus came to have such extreme obliquities. A leading hypothesis is that both experienced massive collisions at some point in their distant past, essentially knocking them over. A glancing blow from a minor planet isn't the only thing that can change an obliquity. The tilt of our planet's axis is drifting - ever so slightly - all the time. The poles actually trace out a rather complex dance over time scales ranging from minutes to thousands of centuries. Like a spinning top, our planet also wobbles - though it does so very slowly. Over a period of 26,000 years, the poles trace out a giant circle in the sky. Right now, the north pole points pretty close to the star Polaris. 365 Days of Astronomy no May 14th: Diamond Planet Finder Is A Star http://365daysofastronomy.org/2012/05/14/may-14th-diamond-planet-finder-is-a-star/ http://365daysofastronomy.org/2012/05/14/may-14th-diamond-planet-finder-is-a-star/#comments Mon, 14 May 2012 11:00:46 +0000 kortney.hogan http://365daysofastronomy.org/?p=7683 Date: May 14, 2012 Title: Diamond Planet Finder Is A Star Podcaster: Michael Greenwell Links: http://michaelgreenwell.wordpress.com/ and http://exitstageright.wordpress.com/ Description: Last year, after making an enormously publicized discovery astronomer Matthew Bailes used his moment of fame to defend his scientific colleagues and to try to point us in the direction in which we need to be looking. I think he should be applauded for this and we would do well to listen to what he had to say. Bio: Michael Greenwell has worked, at various times, as a university tutor, a barman, a DJ (not a very good one), an office lackey, supermarket worker, president of a small charity, a researcher, a librarian, a volunteer worker in Nepal during the civil war there, and some other things that were too tedious to mention. He blogs here and also runs the animal extinction site Exit Stage Right. Today's Sponsor: "This episode of 365 days of Astronomy is sponsored by 'The Heliochromologist' " "This episode of 365 days of astronomy was sponsored by iTelescope.net - Expanding your horizons in astronomy today. The premier on-demand telescope network, at dark sky sites in Spain, New Mexico and Siding Spring, Australia." Transcript: At the end of last August, you probably read about the scientists who found a planet that is, in their words “certainly crystalline” or in other words, a large…. well… ok…a VERY large diamond…in fact, it is about 4 times the diameter of the Earth. The planet orbits a pulsar, which they referred to as Beyonce on account of the amount of Bling it was showing off. The story got a lot of coverage but one of the scientists involved, Matthew Bailes, did something a couple of weeks later that was rather brave and just as worthy of note - and I think that he should be applauded for it and that we would do well to listen to what he had to say. Specifically, he wrote an article for an Australian website called “The Conversation” in which he used the opportunity the extensive media coverage this discovery gave him to defend climate scientists and try to draw people’s attention to a problem that is ever worsening ie the fact that while the media are happy to report about weird weather on Jupiter or Saturn for example, they show a certain reluctance to talk about Global Weirding and the problems of Climate change here on planet Earth. I’ll quote to you now a slightly shortened version of what he said…

Following the publication of our finding in the journal Science, our research received amazing attention from the world’s media. I was asked by many journalists about the significance of the discovery. If I were honest, I’d have to concede that, although worthy of publication in Science, in the field of astrophysics it isn’t that significant. And yet the diamond planet has been hugely successful in igniting public curiosity about the universe in which we live. Imagine for a minute that, instead of discovering a diamond planet, we’d made a breakthrough in global temperature projections. Let’s say we studied computer models of the influence of excessive greenhouse gases, verified them through observations, then had them peer-reviewed and published in Science. Instead of sitting back and basking in the glory, I suspect we’d find a lot of commentators, many with no scientific qualifications, pouring scorn on our findings. People on the fringe of science would be quoted as opponents of our work, arguing that it was nothing more than a theory yet to be conclusively proven. Before long our credibility and findings would be under serious question. But luckily we’re not climate scientists. It may come as a big surprise to many, but there is actually no difference between how science works in astronomy and climate change – or any other scientific discipline for that matter. We make observations, run simulations, test and propose hypotheses, and undergo peer review of our findings. Of course we all make mistakes. But eventually the prevailing wisdom of the community triumphs and the field advances. It’s wonderful to be a part of that process. But on occasion those from the fringe of the scientific community will push a position that is simply not credible against the weight of evidence. This occurs within any discipline. But it seems it’s only in the field of climate science that such people are given airtime and column inches to espouse their views. Those who want to ignore what’s happening to Earth feel they need to be able to quote “alternative studies”, regardless of the scientific merit of those studies. In all fields of science, papers are challenged and statistics are debated. If there is any basis to these challenges they stand, but if not they fall by the wayside and the field continues to advance. When big theories fall, it isn’t because of business or political pressures – it’s because of the scientific process. Sadly, the same media commentators who celebrate diamond planets without question are all too quick to dismiss the latest peer-reviewed evidence that suggests man-made activities are responsible for changes in concentrations of CO2 in our atmosphere. The scientific method is universal. If we selectively ignore it in certain disciplines, we do so at our peril.

"Should the free precession be accepted as the correct explanation of the phenomena, it will give an important tool to study white dwarf equations of state. The theory of compact objects predicts certain relations between the spin and precession periods, and our finding provides a good test for the theory and establishes a qualitative model to be explored both theoretically and observationally. Detection of precession can become a powerful tool in searching for the internal properties of compact stars, which would be otherwise inaccessible for us. Combined with other methods to estimate masses and density of the WDs in CVs, the precession period will help to refine these values, which in turn, allows for testing and proving the theory for the precession of compact stars and may allow for further advances in our knowledge of the structure of WDs and the influence of accretion on them."

Some interesting things were also observed in the quiescent state prompting additional scrutiny during this year's season of the longer term behaviour of the system when at quiescence. It has been great to be a part of the wonderful science research that is still ongoing. Its all part of the great science you can do as a part of any number of citizen science initiatives. The AAVSO and Variable Stars South have many and varied research projects just like this one where you can play a significant part in gathering the data and working with professional astronomers. It was great working with such professional people ably lead by Vitaly and George Sjoberg. Participation in campaigns like this is a great way to get to know other astronomers, and build your credibility as a capable amateur astronomer. End of podcast: 365 Days of Astronomy ===================== The 365 Days of Astronomy Podcast is produced by the Astrosphere New Media Association. Audio post-production by Preston Gibson. Bandwidth donated by libsyn.com and wizzard media. Web design by Clockwork Active Media Systems. You may reproduce and distribute this audio for non-commercial purposes. Please consider supporting the podcast with a few dollars (or Euros!). Visit us on the web at 365DaysOfAstronomy.org or email us at info@365DaysOfAstronomy.org. Until tomorrow...goodbye.]]> http://365daysofastronomy.org/2012/05/10/may-10th-twinkle-twinkle-little-star-how-i-wonder-fs-aur/feed/ 0 podcast iya 365 Date: May 10, 2012 - Title: Twinkle Twinkle little star ...... How I wonder FS Aur? - Podcaster: Peter Lake - Organization: AARTScope Blog - Links: http://aartscope.blogspot.com http://vitaly.neustroev.net/research/observing-campaigns/ http://www. Date: May 10, 2012 Title: Twinkle Twinkle little star ...... How I wonder FS Aur? Podcaster: Peter Lake Organization: AARTScope Blog Links: http://aartscope.blogspot.com http://vitaly.neustroev.net/research/observing-campaigns/ http://www.twitter.com/fs_Aur http://www.aavso.org Description: FS Aur is one of the most strangest and erratic variable Stars. Peter Lake reports on the data collected as part of the broader work with Dr Vitaly Neustroev of the Oulu University Finland and discusses the past two seasons of observations. Peter Lake is an Amateur Astronomer from Melbourne Australia and regularly discusses how people can be involved in citizen science and observation programs. Bio: Peter Lake is an amateur Astronomer from Melbourne, Australia, a member of Variable Stars South and the AAVSO and he owns and operates a 0.5m Planewave CDK Telescope at New Mexico skies, which is affiliated to iTelescope.net. Peter has been a participant in citizen science and recovered asteroid 2000 EV70 during the Spacewatch FMO program. More recently Peter has been actively involved in the study of cataclysmic variable star FS Aur, and followup exoplanet observations on Kepler targets of interest. Sponsor: "This episode of 365 days of astronomy is sponsored with thanks to all non-US contributors for showing us that the night sky is something we can all share." "Additional sponsorship for this episode of 365 days of astronomy was provided by iTelescope.net - Expanding your horizons in astronomy today. The premier on-demand telescope network, at dark sky sites in Spain, New Mexico and Siding Spring, Australia." Transcript: Like duck hunting, Variable Stars have their "Seasons" also. A season being where the variable star in question is in the optimal position for "shooting with CCDs" ie observable for most of the night, during this time ideally it can be visible for as many as 6-7 hours per night. FS Aur is a Cataclysmic Variable is now low in the west at sunset at the close of an intensive second season. So I though it would be good to review these past two seasons, before once again, it comes around for observations in the next northern winter. FS Aur is one of the strangest and complex objects in the extensive variable star family. It is thought to be a magnetic white dwarf and red giant binary Star with a third object acting on it in a circumbinary orbit. (Tovmassian et al., 2010) Back in 2010 there was a sporadic and incomplete light curve and astronomers wanted answers. When they want answers they often leverage the collective effort of the American Association of Variable Star Observers (AAVSO), to muscle up some more observations and data. FS Aur has a number of photometric and spectroscopic cycles going on. On top of this it goes into outburst about every 12-15 days. The outburst duration is so short (2-3 days) it has been regularly missed in the past - so in the 2010/11 season Dr Neustroev rallied a special effort. For the first time, members of the AAVSO mapped the entire outburst cycle, a good number of times. Dr Vitaly Neustroev is the University Researcher (Yliopistotutkija) at the University of Oulu, Finland and he is a key researcher on FS Aur, working hard to better understand its erratic behaviour. Visit the observing campaign page here, and also follow on (Twitter). I like following Cataclysmic Variables, after catching Simostronomy fever, and I have been a regular on FS Aur since Dr Neustroev's call to action. During the campaign FS Aur has been dancing away with a little periodic wobble at about 15.9 with the odd subtle change in brightness, then it goes really dull to 16.2 then literally within 24-36 hours it pops up to magnitude about Mag 14. As an amateur astronomer I am always careful to point out that I'm not qualified to say how or why, but I can tell you when, where and how bright! So what is going on with FS Aur - Dr Neustroev describes it this way: 365 Days of Astronomy no May 9th: Astronomy Word of the Week: Nova http://365daysofastronomy.org/2012/05/09/may-9th-astronomy-word-of-the-week-nova/ http://365daysofastronomy.org/2012/05/09/may-9th-astronomy-word-of-the-week-nova/#comments Wed, 09 May 2012 11:00:09 +0000 kortney.hogan http://365daysofastronomy.org/?p=7650 Date: May 9, 2012 Title: Astronomy Word of the Week: Nova Podcaster: Dr. Christopher Crockett Organization: United States Naval Observatory Links: http://christophercrockett.com http://astrowow.wordpress.com/ Description: Why do once invisible stars suddenly flare up and then slowly fade from view? The astronomy word of the week is "nova". Bio: Dr. Christopher Crockett is an astronomer at the United States Naval Observatory in Flagstaff, Arizona. His research involves searching for planets around very young stars (“only” a few million years old). It is hoped that the results from this research will help constrain models of planet formation and lead to a better understanding of where, when, and how often planets form. Chris is also passionate about astronomy outreach and education and will talk for hours about the Universe if you let him. Sponsors: Sponsorship for this episode of "365 days of Astronomy" is donated anonymously and dedicated to the men and women of NASA who strive to turn science fiction into science reality. Additional sponsorship for this episode has been provided by iTelescope.net - Expanding your horizons in astronomy today. The premier on-demand telescope network, at dark sky sites in Spain, New Mexico and Siding Spring, Australia. Transcript: In 1572, Danish astronomer Tycho Brahe, along with observers around the world, noticed a new star in the constellation Casseiopeia. Rivaling Venus as the brightest object in the night sky after the Moon, the unexpected guest remained visible for nearly two years before fading from view. The appearance of a new star was nothing short of revolutionary; astronomers long agreed that the celestial sphere was unchanging. A transient star challenged this assumption and suggested that the heavens were perhaps more dynamic than originally thought. The celestial intruder came to be known as a "nova" - after Tycho Brahe's extensive manuscript on the phenomenon - where he referred to the object simply by the latin term for a new star: "stella nova". While no one could have known it at the time, the new star was actually not new at all but rather a very old star experiencing a cataclysmic event. Most of the stars in the sky are not singular, like our Sun, but rather members of binary star systems - two stars locked in orbit around one another. Of this pair, one star is often more massive than its companion and therefore burns through its nuclear fuel at a faster rate. The heavier star reaches the end of its life before its sibling. When it does, the star inflates to become a red giant and sheds its outer layers into space leaving behind the hot, dense stellar core. The naked core, known as a "white dwarf", continues to orbit its stellar neighbor while taking the next few billion years to passively cool from a white-hot 100,000 degrees. In the case of close binary pairs, the white dwarf can actually siphon matter off of its companion. The intermingled gravitational fields of the two stars builds a bridge of predominately hydrogen gas spanning the distance between them. Gas from the still active star flows through this gravitational funnel and spills on to the surface of the white dwarf. The mass of the white dwarf controls the rate of mass accretion; if the rate is high enough, then something quite spectacular can happen. White dwarfs are an example of a rather exotic type of matter that physicists call "degenerate". Most gasses expand when you heat them up: the increasing temperature causes the molecules to zip around faster which in turn increases the gas pressure. At extreme densities - like those seen in the cores of stars - the gas behaves rather peculiarly. The pressure is no longer a slave to temperature: turn up the heat and the gas does not expand. This counterintuitive behavior is crucial to what happens next on the white dwarf's surface. As hydrogen from the donor star comes crashing down, the crushing force of gravity compresses it into a degenerate state and the intense radiation heats the gas to many millions of degrees. But having now obtained the properties of a degenerate gas, the newly acquired hydrogen shell doesn't expand in response to the rapid heating, but holds its pressure steady. And now things get interesting. At temperatures exceeding 16 million degrees Celsius, conditions on the surface mimic those deep in the cores of stars and a thermonuclear explosion is the result. Hydrogen is rapidly fused into helium and the resulting release of energy blows the outer hydrogen shell off the surface of the white dwarf at speeds exceeding ten million kilometers per hour. In mere days, the white dwarf can increase its brightness by 100,000 times. It can then take months - or in some cases years - for the star to slowly fade from view. Our Milky Way Galaxy experiences several dozen novae each year, only about ten of which are visible from Earth. A few are even visible to the naked eye. The most recent nova to be seen without the aid of binoculars or telescopes did so in the constellation Scorpius, reaching its peak brightness on February 17, 2007. Even more rare are what astronomers call "recurrent nova". Once the white dwarf has blown the hydrogen shell into space, the gas can slowly start building up again. These are novae that flare up repeatedly, sometimes once a year, sometimes once every couple of decades. In our whole galaxy, only ten novae are known to be recurrent. In the centuries since the new star of 1572, astronomers have come to realize that the event which gave novae their name was not what we know now as a nova. Up until early in the 20th century, a nova referred to any rapid brightening of a star. But there are many reasons stars suddenly flare into view. What Tycho saw was actually something far more powerful - a type of, aptly named, supernova. The supernova of 1572 was not the result of a flash of hydrogen burning on a white dwarf shell, but rather was caused by the complete detonation of a white dwarf. By stealing gas from a nearby companion slowly enough, the progenitor of the supernova delayed a nova flash while gradually increasing its temperature and pressure and eventually igniting hydrogen fusion throughout the interior of the once dead stellar core. With out the counterbalancing force of the rest of the star to throttle these reactions, the now violently active core obliterated itself in one of the most powerful explosions the Universe can produce. The event of 1572 ushered in a new era of astronomy, one in which the constancy of the celestial sphere could no longer be assumed. Novae - and their more powerful supernovae cousins - are constant reminders that we, in fact, live in a highly dynamic and energetic Universe. End of podcast: 365 Days of Astronomy ===================== The 365 Days of Astronomy Podcast is produced by the Astrosphere New Media Association. Audio post-production by Preston Gibson. Bandwidth donated by libsyn.com and wizzard media. Web design by Clockwork Active Media Systems. You may reproduce and distribute this audio for non-commercial purposes. Please consider supporting the podcast with a few dollars (or Euros!). Visit us on the web at 365DaysOfAstronomy.org or email us at info@365DaysOfAstronomy.org. Until tomorrow...goodbye.]]> http://365daysofastronomy.org/2012/05/09/may-9th-astronomy-word-of-the-week-nova/feed/ 0 podcast iya 365 Date: May 9, 2012 - Title: Astronomy Word of the Week: Nova - Podcaster: Dr. Christopher Crockett - Organization: United States Naval Observatory - Links: http://christophercrockett.com http://astrowow.wordpress.com/ - Date: May 9, 2012 Title: Astronomy Word of the Week: Nova Podcaster: Dr. Christopher Crockett Organization: United States Naval Observatory Links: http://christophercrockett.com http://astrowow.wordpress.com/ Description: Why do once invisible stars suddenly flare up and then slowly fade from view? The astronomy word of the week is "nova". Bio: Dr. Christopher Crockett is an astronomer at the United States Naval Observatory in Flagstaff, Arizona. His research involves searching for planets around very young stars (“only” a few million years old). It is hoped that the results from this research will help constrain models of planet formation and lead to a better understanding of where, when, and how often planets form. Chris is also passionate about astronomy outreach and education and will talk for hours about the Universe if you let him. Sponsors: Sponsorship for this episode of "365 days of Astronomy" is donated anonymously and dedicated to the men and women of NASA who strive to turn science fiction into science reality. Additional sponsorship for this episode has been provided by iTelescope.net - Expanding your horizons in astronomy today. The premier on-demand telescope network, at dark sky sites in Spain, New Mexico and Siding Spring, Australia. Transcript: In 1572, Danish astronomer Tycho Brahe, along with observers around the world, noticed a new star in the constellation Casseiopeia. Rivaling Venus as the brightest object in the night sky after the Moon, the unexpected guest remained visible for nearly two years before fading from view. The appearance of a new star was nothing short of revolutionary; astronomers long agreed that the celestial sphere was unchanging. A transient star challenged this assumption and suggested that the heavens were perhaps more dynamic than originally thought. The celestial intruder came to be known as a "nova" - after Tycho Brahe's extensive manuscript on the phenomenon - where he referred to the object simply by the latin term for a new star: "stella nova". While no one could have known it at the time, the new star was actually not new at all but rather a very old star experiencing a cataclysmic event. Most of the stars in the sky are not singular, like our Sun, but rather members of binary star systems - two stars locked in orbit around one another. Of this pair, one star is often more massive than its companion and therefore burns through its nuclear fuel at a faster rate. The heavier star reaches the end of its life before its sibling. When it does, the star inflates to become a red giant and sheds its outer layers into space leaving behind the hot, dense stellar core. The naked core, known as a "white dwarf", continues to orbit its stellar neighbor while taking the next few billion years to passively cool from a white-hot 100,000 degrees. In the case of close binary pairs, the white dwarf can actually siphon matter off of its companion. The intermingled gravitational fields of the two stars builds a bridge of predominately hydrogen gas spanning the distance between them. Gas from the still active star flows through this gravitational funnel and spills on to the surface of the white dwarf. The mass of the white dwarf controls the rate of mass accretion; if the rate is high enough, then something quite spectacular can happen. White dwarfs are an example of a rather exotic type of matter that physicists call "degenerate". Most gasses expand when you heat them up: the increasing temperature causes the molecules to zip around faster which in turn increases the gas pressure. At extreme densities - like those seen in the cores of stars - the gas behaves rather peculiarly. The pressure is no longer a slave to temperature: turn up the heat and the gas does not expand. This counterintuitive behavior is crucial to what happens next on the white dwarf's surface. As hydrogen from the donor star comes crashing down, 365 Days of Astronomy no May 8th: What is Black http://365daysofastronomy.org/2012/05/08/may-8th-what-is-black/ http://365daysofastronomy.org/2012/05/08/may-8th-what-is-black/#comments Tue, 08 May 2012 11:00:41 +0000 kortney.hogan http://365daysofastronomy.org/?p=7646 Date: May 8, 2012 Title: What is Black Podcaster: Rob Sparks & Dr. Steven Pompea Organization: NOAO Links: www.noao.edu Description: Most people think of black as a color, but black is really the absence of light. Truly black surfaces reflect almost none of the light that falls on them. In this podcast, Dr. Stephen Pompea discusses black surface, how they are produced and why they are important in astronomy and other sciences. Bio: Rob Sparks is a science education specialist in the EPO group at NOAO and works on the Galileoscope project (www.galileoscope.org), providing design, dissemination and professional development. He also pens a great blog at halfastro.wordpress.com. Dr. Stephen Pompea did his undergraduate work in physics, space physics, and astronomy at Rice University, his Master’s work in physics teaching at Colorado State University, and his Ph.D. in astronomy at the University of Arizona. He is currently the manager of the Education and Public Outreach Group at the National Optical Astronomy Observatory. Sponsor: This episode of the 365 Days of Astronomy podcast is sponsored by the National Optical Astronomy Observatory. NOAO is a US national research and development center for ground-based nighttime astronomy. We provide astronomers access to world-class observing facilities on a peer-reviewed basis. Our mission is to engage in programs to develop the next generation of telescopes, instruments, and software tools necessary to enable exploration and investigation through the observable Universe. For information on observing proposals or our public programs, please visit www.noao.edu for more information. "This episode has also been sponsored by the Lake County Astronomical Society: Celebrating 30 years of stellar service to members and the public." Transcript: *** Transcript coming soon. *** End of podcast: 365 Days of Astronomy ===================== The 365 Days of Astronomy Podcast is produced by the Astrosphere New Media Association. Audio post-production by Preston Gibson. Bandwidth donated by libsyn.com and wizzard media. Web design by Clockwork Active Media Systems. You may reproduce and distribute this audio for non-commercial purposes. Please consider supporting the podcast with a few dollars (or Euros!). Visit us on the web at 365DaysOfAstronomy.org or email us at info@365DaysOfAstronomy.org. Until tomorrow...goodbye.]]> http://365daysofastronomy.org/2012/05/08/may-8th-what-is-black/feed/ 0 podcast iya 365 Date: May 8, 2012 - Title: What is Black - Podcaster: Rob Sparks & Dr. Steven Pompea - Organization: NOAO - Links: www.noao.edu - Description: Most people think of black as a color, but black is really the absence of light. Date: May 8, 2012 Title: What is Black Podcaster: Rob Sparks & Dr. Steven Pompea Organization: NOAO Links: www.noao.edu Description: Most people think of black as a color, but black is really the absence of light. Truly black surfaces reflect almost none of the light that falls on them. In this podcast, Dr. Stephen Pompea discusses black surface, how they are produced and why they are important in astronomy and other sciences. Bio: Rob Sparks is a science education specialist in the EPO group at NOAO and works on the Galileoscope project (www.galileoscope.org), providing design, dissemination and professional development. He also pens a great blog at halfastro.wordpress.com. Dr. Stephen Pompea did his undergraduate work in physics, space physics, and astronomy at Rice University, his Master’s work in physics teaching at Colorado State University, and his Ph.D. in astronomy at the University of Arizona. He is currently the manager of the Education and Public Outreach Group at the National Optical Astronomy Observatory. Sponsor: This episode of the 365 Days of Astronomy podcast is sponsored by the National Optical Astronomy Observatory. NOAO is a US national research and development center for ground-based nighttime astronomy. We provide astronomers access to world-class observing facilities on a peer-reviewed basis. Our mission is to engage in programs to develop the next generation of telescopes, instruments, and software tools necessary to enable exploration and investigation through the observable Universe. For information on observing proposals or our public programs, please visit www.noao.edu for more information. "This episode has also been sponsored by the Lake County Astronomical Society: Celebrating 30 years of stellar service to members and the public." Transcript: *** Transcript coming soon. *** End of podcast: 365 Days of Astronomy ===================== The 365 Days of Astronomy Podcast is produced by the Astrosphere New Media Association. Audio post-production by Preston Gibson. Bandwidth donated by libsyn.com and wizzard media. Web design by Clockwork Active Media Systems. You may reproduce and distribute this audio for non-commercial purposes. Please consider supporting the podcast with a few dollars (or Euros!). Visit us on the web at 365DaysOfAstronomy.org or email us at info@365DaysOfAstronomy.org. Until tomorrow...goodbye. 365 Days of Astronomy no May 7th: The Late Heavy Bombardment — an Extended Version? http://365daysofastronomy.org/2012/05/12/may-12th-encore-our-place-in-space/ http://365daysofastronomy.org/2012/05/12/may-12th-encore-our-place-in-space/#comments Sat, 12 May 2012 11:00:59 +0000 kortney.hogan http://365daysofastronomy.org/?p=7675 Date: May 12, 2012 Title: Encore: Our Place in Space Podcaster: Pamela Gay Organization: Astronomy Cast, Star Stryder This podcast originally aired on May 18th, 2010 http://365daysofastronomy.org/2010/05/18/may-18th-our-place-in-space/ Description: From the surface of the Earth, it is easy to feel safe, and in control because we have the knowledge to understand the universe. But we are small, and life is fragile in this vast universe, and there are more things in heaven and earth waiting to be discovered than are dreamt of in all our sciences. In this podcast I try and provide context on both out place in time and in space, and just how fragile our human existence really is. Bio: Dr. Pamela Gay is a professor at Southern Illinois University-Edwardsville. She is also an astronomer, writer, and podcaster focused on using new media to engage people in science and technology. Listen to her weekly on one of the most popular astronomy podcasts, Astronomy Cast. Follow her on her blog, Star Stryder. Sponsor:This episode of 365 days of astronomy was sponsored by iTelescope.net - Expanding your horizons in astronomy today. The premier on-demand telescope network, at dark sky sites in Spain, New Mexico and Siding Spring, Australia. Transcript: Welcome to 365 Days of Astronomy. This is Pamela Gay of Astronomy Cast and StarStryder.com coming to you from Southern Illinois. On this Rainy spring day it seems like all the world is in my backyard, and most of it is triggering hay fever. The truth is, h ere on the surface of the Earth it is easy to see our universe as small and understood. Each year the seasons tick past in explainable ways, and 400 years after Kepler, the motion of the planets is just something we take for granted. Solar eclipses no longer make people tremble as the Asseryians trembled on the battlefield during the 763BC, instead the tremble in anticipation of the perfect picture during the astronomical eclipse tours. Today eclipses are just a roughly twice a year things that thousands of people turn into vacations. From the surface of the Earth, it is easy to feel safe, and in control because we have the knowledge to understand the universe. We have science to explain the supernovae, the comets, the every twinkle and gleam in the sky. But we are small, and life is fragile in this vast universe, and there are more things in heaven and earth waiting to be discovered than are dreamt of in all our sciences. Our human minds struggles to grasp at the scale of our universe. Any number over a million is simply large, and in discussing the cosmos, we discuss the billions and billions of galaxies, the billions and billions of stars, and distances so vaste that light has not yet had time to travel from most distant galaxies we see in the north to the most distant galaxies we see in our Southern skies. In this universe defined by unimaginable billions, it is easy to lose track of our place in the context of space. Carl Sagan referred to the earth as a Pale Blue Dot and in images taken by the Cassini space probe as orbited Saturn, we can see the distant Earth in its smallness. Sagan wrote of our world, “Look again at that dot. That’s here, that’s home, that’s us. On it everyone you love, everyone you know, everyone you ever heard of, every human being who ever was, lived out their lives. The aggregate of our joy and suffering, thousands of confident religions, ideologies, and economic doctrines, … every king and peasant, every young couple in love, every mother and father, hopeful child, inventor and explorer, every teacher of morals, every corrupt politician, every ’superstar,’ every ’supreme leader,’ every saint and sinner in the history of our species lived there – on a mote of dust suspended in a sunbeam.” Sagan worked to express our smallness, but this isn’t our only struggle. We also struggle to understand our place in the vastness of time. Our planet is a transitory thing. Formed roughly 4.5 billion years ago, it will be able to support life for only another 50 million years before the Sun’s slow increase in temperature makes life intolerable on Earth. In roughly 5 billion years our Earth will be destroyed entirely as our Sun bloats into a red giant and either consumes the planet or simply broils it with intense solar winds. We live in the twilight years of our world, and time is ticking. But our planet is just part of a cycle. We live on a rocky world orbiting a star that is rich in heavy elements. If you shine sunlight through the most amazing of prisms to make a rainbow, you will be able to single out dark stripes mixed in the light, many of which arise from Iron, Titanium, and other metallic atoms in the sun’s atmosphere. To get at this richness of atomic diversity, our universe had to be created, and generations of stars had to live and die, all before our own Sun could be born. When our universe formed, 13.7 billion years ago, it was pure energy – pure light. Within the first fractions of a second, that energy began to solidify into particles. Mass and Energy are just two faces of the same thing, and as the universe cooled, the mass divided from the light. At first there was matter and anti-matter, but through the miracle of asymmetry, for every 1 billion anti-matter particles there was a billion and 1 matter particles. The particles collided – they destroyed one another, and they left behind matter. And that matter, at that moment, and for almost the next 3 minutes, was as hot and as dense as the center of a star and nuclear fusion was able to take place. Protons combined. Neutrons were created. Hydrogen nuclei grew into deuterium, which in turn fused to helium and trace amounts of lithium and beryllium. Our theories tell us the ratios of these reactions, and when we look out at the oldest stars, we find the correct fractions fossilized in the elemental abundances of these ancient stars’ light. This is just one of many lines of evidence proving the big bang. After the first 3 minutes, nuclear reactions shut off, but the universe was still too hot for neutral atoms to form. Everything was an opaque mash of nuclei and electrons and light, colliding. It stayed too hot, and it stayed opaque for nearly 300,000 years, but then one day it cooled enough that the electrons could bond with the atomic nuclei, and when that happened the light was released. Today we see this escaping light as the cosmic microwave background. The cosmic microwave background demarks the point beyond which we can never observe. It is like the barrier beyond which your headlamp just can’t reach when scuba diving, or that place in the fog your candle cannot illuminate because it’s just too far away. Our universe, within this shell, is 93 billion light years across, but what we can see is likely no more than a few percent of the whole. But it is all the universe we will ever know. We live on just one small pale blue dot orbiting a metal rich star. We exist because matter and anti matter were formed in unequal parts. We exist because the universe’s density was just right. We exist, because other stars formed, created heavy elements, and died, distributing the elements back into space to form our world and others. And most amazingly of all, we live in a universe that is at once something we can learn to understand and something that is beyond our imagining. Every day we are finding new things that defy our theories and force us to expand our ideas – We now know 26% of the universe is made of dark matter – a material like nothing experienced here on earth – and 70% of the universe is contained in dark energy – something we know so little about all we can really do is say we have a name for this rather large blank are in our scientific understanding. And every day we discover new planets in places we never imaged. New galaxies. New types of objects – all things we would have never imagined in our wildest science fiction. The most amazing thing about science is that it works, and through its equations and rules we can build an understanding a universe that it beyond the ability of a single man or woman to full understand and visualize. Our universe is vast and old, and we are but small fragile creature brief in our time on this earth. But for all our smallness, we do understand our universe through science. In this show I only had 10 minutes to tell you about our small place in space. If you’d like to learn more, please tune in to Astronomy Cast with Fraser Cain and myself, or read my blog at starstryder.com End of podcast: 365 Days of Astronomy ===================== The 365 Days of Astronomy Podcast is produced by the Astrosphere New Media Association. Audio post-production by Preston Gibson. Bandwidth donated by libsyn.com and wizzard media. Web design by Clockwork Active Media Systems. You may reproduce and distribute this audio for non-commercial purposes. Please consider supporting the podcast with a few dollars (or Euros!). Visit us on the web at 365DaysOfAstronomy.org or email us at info@365DaysOfAstronomy.org. Until tomorrow...goodbye.]]> http://365daysofastronomy.org/2012/05/12/may-12th-encore-our-place-in-space/feed/ 0 podcast iya 365 Date: May 12, 2012 - Title: Encore: Our Place in Space - Podcaster: Pamela Gay - Organization: Astronomy Cast, Star Stryder - This podcast originally aired on May 18th, 2010 http://365daysofastronomy.org/2010/05/18/may-18th-our-place-in-space/ - Date: May 12, 2012 Title: Encore: Our Place in Space Podcaster: Pamela Gay Organization: Astronomy Cast, Star Stryder This podcast originally aired on May 18th, 2010 http://365daysofastronomy.org/2010/05/18/may-18th-our-place-in-space/ Description: From the surface of the Earth, it is easy to feel safe, and in control because we have the knowledge to understand the universe. But we are small, and life is fragile in this vast universe, and there are more things in heaven and earth waiting to be discovered than are dreamt of in all our sciences. In this podcast I try and provide context on both out place in time and in space, and just how fragile our human existence really is. Bio: Dr. Pamela Gay is a professor at Southern Illinois University-Edwardsville. She is also an astronomer, writer, and podcaster focused on using new media to engage people in science and technology. Listen to her weekly on one of the most popular astronomy podcasts, Astronomy Cast. Follow her on her blog, Star Stryder. Sponsor:This episode of 365 days of astronomy was sponsored by iTelescope.net - Expanding your horizons in astronomy today. The premier on-demand telescope network, at dark sky sites in Spain, New Mexico and Siding Spring, Australia. Transcript: Welcome to 365 Days of Astronomy. This is Pamela Gay of Astronomy Cast and StarStryder.com coming to you from Southern Illinois. On this Rainy spring day it seems like all the world is in my backyard, and most of it is triggering hay fever. The truth is, h ere on the surface of the Earth it is easy to see our universe as small and understood. Each year the seasons tick past in explainable ways, and 400 years after Kepler, the motion of the planets is just something we take for granted. Solar eclipses no longer make people tremble as the Asseryians trembled on the battlefield during the 763BC, instead the tremble in anticipation of the perfect picture during the astronomical eclipse tours. Today eclipses are just a roughly twice a year things that thousands of people turn into vacations. From the surface of the Earth, it is easy to feel safe, and in control because we have the knowledge to understand the universe. We have science to explain the supernovae, the comets, the every twinkle and gleam in the sky. But we are small, and life is fragile in this vast universe, and there are more things in heaven and earth waiting to be discovered than are dreamt of in all our sciences. Our human minds struggles to grasp at the scale of our universe. Any number over a million is simply large, and in discussing the cosmos, we discuss the billions and billions of galaxies, the billions and billions of stars, and distances so vaste that light has not yet had time to travel from most distant galaxies we see in the north to the most distant galaxies we see in our Southern skies. In this universe defined by unimaginable billions, it is easy to lose track of our place in the context of space. Carl Sagan referred to the earth as a Pale Blue Dot and in images taken by the Cassini space probe as orbited Saturn, we can see the distant Earth in its smallness. Sagan wrote of our world, “Look again at that dot. That’s here, that’s home, that’s us. On it everyone you love, everyone you know, everyone you ever heard of, every human being who ever was, lived out their lives. The aggregate of our joy and suffering, thousands of confident religions, ideologies, and economic doctrines, … every king and peasant, every young couple in love, every mother and father, hopeful child, inventor and explorer, every teacher of morals, every corrupt politician, every ’superstar,’ every ’supreme leader,’ every saint and sinner in the history of our species lived there – on a mote of dust suspended in a sunbeam.” Sagan worked to express our smallness, but this isn’t our only struggle. We also struggle to understand our place in the vastness of time. 365 Days of Astronomy no 365 Days of Astronomy http://365daysofastronomy.org An astronomy podcast every day, all year Wed, 16 May 2012 11:00:41 +0000 en hourly 1 http://wordpress.org/?v=3.1 An astronomy podcast every day, all year 365 Days of Astronomy no An astronomy podcast every day, all year 365 Days of Astronomy http://365daysofastronomy.org/wp-content/plugins/powerpress/rss_default.jpg http://365daysofastronomy.org May 16th: GPS http://365daysofastronomy.org/2012/05/16/may-16th-gps/ http://365daysofastronomy.org/2012/05/16/may-16th-gps/#comments Wed, 16 May 2012 11:00:41 +0000 kortney.hogan http://365daysofastronomy.org/?p=7689 Date: May 16, 2012 Title: GPS Podcaster: Steve Nerlich Organization: Cheap Astronomy Links: www.cheapastro.com Description: Cheap Astronomy once again demonstrates that pretty much everything in life has a connection to astronomy. Bio: Cheap Astronomy offers an educational website because in space no-one can hear you podcast. Today's Sponsor: "This episode of 365 days of Astronomy" is sponsored by the Lake County Astronomical Society: Celebrating 30 years of stellar service to members and the public." Additional sponsorship for this episode has also been provided by iTelescope.net - Expanding your horizons in astronomy today. The premier on-demand telescope network, at dark sky sites in Spain, New Mexico and Siding Spring, Australia. Transcript: Hi this is Steve Nerlich from Cheap Astronomy www.cheapastro.com and this is GPS OK – If you don’t have one, you know someone who does, so let’s skip the introductions and get straight down to the astronomy. A standard GPS configuration is a constellation of 24 GPS satellites. The satellites are all at an altitude of 20,200 km with an orbital period of 11 hours and 58 minutes – which means they do exactly 2 orbits for each time the Earth spins once on its axis. Four satellites each follow six orbital planes separated by 60 degrees which surround the Earth in an (airquotes) ‘birdcage’ of criss-crossing orbits. There a link to the relevant Wikipedia article from the Cheap Astronomy podcast page which has a nice animation of a GPS satellite constellation. At last count, there were actually 31 actively transmitting GPS satellites – with these extra number increasing location accuracy and redundancy. There’s been some recent media regarding a growing risk of dropping below the minimum 24 active satellites required to make GPS work effectively, but it remains to be seen if this risk will be realised in the face of the increasing economic importance of maintaining a working GPS system. A GPS satellite broadcasts a signal indicating where it is and the time the signal was broadcast – your receiver then determines, from the time it receives that signal, the distance travelled by the signal, knowing that, being a radio transmission, the signal travels at the speed of light. By making just four calculations from four satellites in the sky, your GPS receiver can then establish its position with respect to latitude, longitude and altitude. It’s all about the conjunction of spheres. Imagine one satellite broadcasting a radio signal. If you pick up that signal and determine it’s a 100 km away, all you really know is that you are somewhere on a surface of a sphere with a 100 km radius that has the satellite at its centre. If there’s two such satellites then you’ll know you are somewhere on the circumference of a circle representing the plane where the two spheres of radio broadcast overlap. Introduce a third satellite and you can narrow down your location to just two points in space which are the points where two differently orientated circle circumferences intersect. Potentially this may be enough to roughly determine your position since you can anticipate you will be on the one of those two points corresponding to the surface of the Earth. But for strictest accuracy – including accuracy in determining your altitude above sea level, the signal from a fourth satellite is required. And that is the idea of the constellation of GPS satellites. Keeping 24 satellites moving in the same orbit, tracing a birdcage of divergent paths around the globe ensures there will always be four satellites in the sky wherever you happen to be on Earth. Now when I say GPS satellites just have to broadcast where they are – actually knowing where they are is a whole separate operation, While the orbital period is predictable, knowing at what point they are on that orbit requires some very accurate time keeping – for which reason each satellite has an atomic clock. Nonetheless, even this isn’t enough, as the orbital paths of the satellites are subject to slight shifting due to the gravitational influence of the Sun and the Moon. To keep track of these changes the satellites are monitored from a fixed, known location on the Earth’s surface – a function currently managed by the 50th Space Wing of the US Airforce Space Command – seriously. Now, given that your GPS receiver is working out its distance from each of four satellites based solely on the time lag of a signal moving at the speed of light from a satellite just over 20,000 kilometres away – there is considerable potential for a margin of error that could see you driving over the embankment into a river when that sexy voice says ‘turn left now’. There are a range of methods to deal with various sources of error. Firstly your GPS receiver carries an electronic almanac of which satellite should be where since confusion can arise when the satellite radio signals get reflected off surroundings, such as tall buildings. This electronic almanac is constructed from calibration data received from the GPS satellites, although these data are generally relayed from a ground-based source – such as Airforce Space Command. The almanac helps your receiver distinguish between garbage signals and genuine GPS signals. The receiver also receives time checks from the satellites since, most GPS receivers determine time from a cheap (not that there’s anything wrong with that) quartz clock rather than the ultra-accurate atomic clocks of the satellites. Clock error is probably the biggest potential source of GPS error, which is why, even though you could almost get away with determining your position from just 3 satellites, it is the fourth reading (which we might call quadrangulation) that ensures the poorer accuracy of the GPS receiver’s clock is effectively accounted for. Interestingly, there’s also relativistic effects to account for, since the satellites move in a weaker gravity field (meaning by general relativity their clocks run faster), and they also move at speed relative to the surface of the Earth (meaning by special relativity their clocks run slower). It turns out that the nett effect is that the satellites’ clocks run about 38 microseconds per day faster than they would at the Earth’s surface. To account for this, the clocks are actually set to run at a slightly lower rate, to keep pace with clocks running on the Earth’s surface. In the world of atomic clocks, various time keeping callibrations are also required to account for changes in the rotation of the Earth – which is influenced by the tidal drag of the Moon , the inertia of the Earth’s molten interior and even the melting of glaciers. Overall, the Earth’s rotation is slowing, leading to a lengthening of a solar day. Consequently a leap second must be introduced to atomic timepieces which measure Universal Coordinated Time (known as UTC – because of the French). In fact, a leap second is required to be added to UTC every 18 months or so because each year (on average) the length of a solar day increases by about 0.002 seconds. The atomic clocks of GPS satellites were aligned to UTC in 1980 – but as of 2009, these atomic clocks in orbit now vary by 19 seconds and to keep it simple we just say they are running at GPS time. Various under-the-hood adjustments are made along the way so that your GPS receiver can tell you the local time wherever you happen to be – as well as telling you where you are of course to within… well, within 10 metres is the general benchmark, although this takes a few minutes to establish after the unit is turned on and the accuracy will degrade with tall trees or buildings around. So, you know, it’s a guide – not an absolute – it’s still a good idea to keep one eye on the road. Thanks for listening. This is Steve Nerlich from Cheap Astronomy, www.cheapastro.com. Cheap Astronomy offers an educational website where you can’t put a price on space. No ads, no profit, just good science. Bye. End of podcast: 365 Days of Astronomy ===================== The 365 Days of Astronomy Podcast is produced by the New Media Working Group of the International Year of Astronomy 2009. Audio post-production by Preston Gibson. Bandwidth donated by libsyn.com and wizzard media. Web design by Clockwork Active Media Systems. You may reproduce and distribute this audio for non-commercial purposes. Please consider supporting the podcast with a few dollars (or Euros!). Visit us on the web at 365DaysOfAstronomy.org or email us at info@365DaysOfAstronomy.org. Until tomorrow...goodbye.]]> http://365daysofastronomy.org/2012/05/16/may-16th-gps/feed/ 0 podcast iya 365 Date: May 16, 2012 - Title: GPS Podcaster: Steve Nerlich - Organization: Cheap Astronomy - Links: www.cheapastro.com - Description: Cheap Astronomy once again demonstrates that pretty much everything in life has a connection to astronomy. - Date: May 16, 2012 Title: GPS Podcaster: Steve Nerlich Organization: Cheap Astronomy Links: www.cheapastro.com Description: Cheap Astronomy once again demonstrates that pretty much everything in life has a connection to astronomy. B... 365 Days of Astronomy no May 15th: Astronomy Word of the Week: Obliquity http://365daysofastronomy.org/2012/05/15/may-15th-astronomy-word-of-the-week-obliquity/ http://365daysofastronomy.org/2012/05/15/may-15th-astronomy-word-of-the-week-obliquity/#comments Tue, 15 May 2012 11:00:14 +0000 kortney.hogan http://365daysofastronomy.org/?p=7687 Date: May 15, 2012 Title: Astronomy Word of the Week: Obliquity Podcaster: Dr. Christopher Crockett Organization: United States Naval Observatory Links: http://christophercrockett.com http://astrowow.wordpress.com/ Description: The tilt of our planet is about much more than the seasons. The astronomy word of the week is "obliquity". Bio: Dr. Christopher Crockett is an astronomer at the United States Naval Observatory in Flagstaff, Arizona. His research involves searching for planets around very young stars (“only” a few million years old). It is hoped that the results from this research will help constrain models of planet formation and lead to a better understanding of where, when, and how often planets form. Chris is also passionate about astronomy outreach and education and will talk for hours about the Universe if you let him. Today's Sponsor: "This episode of 365 days of Astronomy" is sponsored by iTelescope.net - Expanding your horizons in astronomy today. The premier on-demand telescope network, at dark sky sites in Spain, New Mexico and Siding Spring, Australia. This episode has also been sponsored by Lake County Astronomical Society: Celebrating 30 years of stellar service to members and the public. Transcript: The planet you're standing on is not very steady. She bobs and wobbles, ducks and weaves, as she makes her annual trek around the Sun. Our home constantly struggles with forces both external and internal; the Sun, the Moon, and the planets tug her back and forth while shifting masses within force her to constantly find new balance. The tilt of our planet's axis - what astronomers call its obliquity - is one measure of this interplanetary tug-of-war. Obliquity measures how far over a planet or moon is tipped relative to its orbit; in the Earth's case, it's about 23 degrees. We feel the obliquity in the changing seasons. In June, the north pole is tipped towards the Sun. The northern hemisphere experiences longer days and more direct sunlight giving us warm summer days. In December, the north pole is tipped away from the Sun and everyone above the equator experiences the bitter chill of winter as the days get shorter and the sunlight reaches us more obliquely. The other planets in our solar system exhibit a wide range of obliquities. Mars, Saturn, and Neptune are all tipped by roughly the same amount as Earth. Mercury and Jupiter have hardly any obliquity at all - which means no seasons for them. Venus' obliquity is 177 degrees; it is almost completely upside down. Put another way, it rotates in the opposite direction from Earth. Were there ever to be a break in Venus' stifling cloud layer, native Venusians would see the Sun rise in the west and set in the east! Uranus is another strange character; his obliquity is 97 degrees. Uranus is lying on his side! This leads to some very strange days and seasons. Each pole of Uranus alternates between being in constant sunlight for 42 years, then perpetual darkness for another 42 years. Only a very thin strip along the equator experiences anything like day/night cycles that we experience - and even then the Sun is frequently sitting very low on the horizon. Astronomers aren't entirely certain how Venus and Uranus came to have such extreme obliquities. A leading hypothesis is that both experienced massive collisions at some point in their distant past, essentially knocking them over. A glancing blow from a minor planet isn't the only thing that can change an obliquity. The tilt of our planet's axis is drifting - ever so slightly - all the time. The poles actually trace out a rather complex dance over time scales ranging from minutes to thousands of centuries. Like a spinning top, our planet also wobbles - though it does so very slowly. Over a period of 26,000 years, the poles trace out a giant circle in the sky. Right now, the north pole points pretty close to the star Polaris. But over time that will change, and in some epochs it will be pointing at nothing at all. This wobble - or precession - doesn't change the amount of obliquity; it simply changes where in space the poles are pointing. The Moon, however, does tug on our planet's axis. In addition to rotation and precession, the Earth experiences something called nutation. This is a slight rocking of the Earth's axis caused by the changing positions of the Moon, the Sun, and all the other bodies in the solar system. With many players involved, the motion from nutation is fairly complex. The main component nods the planet by a couple hundred meters over a nearly 19 year cycle that is tied to how the Moon's orbit drifts around the Earth. Our planet also has to contend with forces much closer to home. Internal motions of magma, deep sea currents, changing ocean salinity, winds, melting ice sheets, and even earthquakes all conspire to constantly change the distribution of mass within the Earth. The planet responds by continuously shifting its spin axis - an effect known as polar motion. This is a bit different than nutation; it actually changes where on Earth the north and south poles are located. Hard as it may be to fathom, these are not fixed locations on the globe. The drift is very small - centimeters per year - but it does add a complex twist to understanding our planets motion in space. The presence of a large moon is believed to help stabilize our obliquity. The tilt does change by a few degrees over many millions of years, but manages to hold steady at around 20-25 degrees. Mars, conversely, appears to be going through a chaotic evolution in its obliquity. Computer simulations of its stability suggest that, over the past few million years, the Red Planet's tilt has oscillated wildly between zero and sixty degrees which may lead to drastic swings in the environment. Many astrobiologists - scientists who study the evolution and origin of life in a cosmic context - argue that our moon may be an essential ingredient for providing a stable environment within which life could thrive. Does this mean that the existence of complex life and advanced civilizations is dependent on the presence of a large satellite? That's hard to say. It is certainly plausible that our closest neighbor in space has been an indispensable partner in the evolution of our species. I'm continually amazed at how a simple concept - like the tilt of a planet - can actually lead down a labyrinthian path of subtleties. Studying Earth's obliquity, and the obliquity of all the other planets and moons, reveals much about the dynamics of our planet, the interplay of our home and neighboring worlds, and even the often times cataclysmic evolution of the solar system. While the subtleties are far removed from our day-to-day lives, our Earth's position in space actually is inseparable from the human experience. The June solstice is just over a month away. Whether you're bundling up for winter, or heading to the beach for summer, remember: the Earth's obliquity is the reason for the seasons! End of podcast: 365 Days of Astronomy ===================== The 365 Days of Astronomy Podcast is produced by the New Media Working Group of the International Year of Astronomy 2009. Audio post-production by Preston Gibson. Bandwidth donated by libsyn.com and wizzard media. Web design by Clockwork Active Media Systems. You may reproduce and distribute this audio for non-commercial purposes. Please consider supporting the podcast with a few dollars (or Euros!). Visit us on the web at 365DaysOfAstronomy.org or email us at info@365DaysOfAstronomy.org. Until tomorrow...goodbye.]]> http://365daysofastronomy.org/2012/05/15/may-15th-astronomy-word-of-the-week-obliquity/feed/ 0 podcast iya 365 Date: May 15, 2012 - Title: Astronomy Word of the Week: Obliquity Podcaster: Dr. Christopher Crockett - Organization: United States Naval Observatory - Links: http://christophercrockett.com http://astrowow.wordpress.com/ - Date: May 15, 2012 Title: Astronomy Word of the Week: Obliquity Podcaster: Dr. Christopher Crockett Organization: United States Naval Observatory Links: http://christophercrockett.com http://astrowow.wordpress.com/ Description: The tilt of our planet is about much more than the seasons. The astronomy word of the week is "obliquity". Bio: Dr. Christopher Crockett is an astronomer at the United States Naval Observatory in Flagstaff, Arizona. His research involves searching for planets around very young stars (“only” a few million years old). It is hoped that the results from this research will help constrain models of planet formation and lead to a better understanding of where, when, and how often planets form. Chris is also passionate about astronomy outreach and education and will talk for hours about the Universe if you let him. Today's Sponsor: "This episode of 365 days of Astronomy" is sponsored by iTelescope.net - Expanding your horizons in astronomy today. The premier on-demand telescope network, at dark sky sites in Spain, New Mexico and Siding Spring, Australia. This episode has also been sponsored by Lake County Astronomical Society: Celebrating 30 years of stellar service to members and the public. Transcript: The planet you're standing on is not very steady. She bobs and wobbles, ducks and weaves, as she makes her annual trek around the Sun. Our home constantly struggles with forces both external and internal; the Sun, the Moon, and the planets tug her back and forth while shifting masses within force her to constantly find new balance. The tilt of our planet's axis - what astronomers call its obliquity - is one measure of this interplanetary tug-of-war. Obliquity measures how far over a planet or moon is tipped relative to its orbit; in the Earth's case, it's about 23 degrees. We feel the obliquity in the changing seasons. In June, the north pole is tipped towards the Sun. The northern hemisphere experiences longer days and more direct sunlight giving us warm summer days. In December, the north pole is tipped away from the Sun and everyone above the equator experiences the bitter chill of winter as the days get shorter and the sunlight reaches us more obliquely. The other planets in our solar system exhibit a wide range of obliquities. Mars, Saturn, and Neptune are all tipped by roughly the same amount as Earth. Mercury and Jupiter have hardly any obliquity at all - which means no seasons for them. Venus' obliquity is 177 degrees; it is almost completely upside down. Put another way, it rotates in the opposite direction from Earth. Were there ever to be a break in Venus' stifling cloud layer, native Venusians would see the Sun rise in the west and set in the east! Uranus is another strange character; his obliquity is 97 degrees. Uranus is lying on his side! This leads to some very strange days and seasons. Each pole of Uranus alternates between being in constant sunlight for 42 years, then perpetual darkness for another 42 years. Only a very thin strip along the equator experiences anything like day/night cycles that we experience - and even then the Sun is frequently sitting very low on the horizon. Astronomers aren't entirely certain how Venus and Uranus came to have such extreme obliquities. A leading hypothesis is that both experienced massive collisions at some point in their distant past, essentially knocking them over. A glancing blow from a minor planet isn't the only thing that can change an obliquity. The tilt of our planet's axis is drifting - ever so slightly - all the time. The poles actually trace out a rather complex dance over time scales ranging from minutes to thousands of centuries. Like a spinning top, our planet also wobbles - though it does so very slowly. Over a period of 26,000 years, the poles trace out a giant circle in the sky. Right now, the north pole points pretty close to the star Polaris. 365 Days of Astronomy no May 14th: Diamond Planet Finder Is A Star http://365daysofastronomy.org/2012/05/14/may-14th-diamond-planet-finder-is-a-star/ http://365daysofastronomy.org/2012/05/14/may-14th-diamond-planet-finder-is-a-star/#comments Mon, 14 May 2012 11:00:46 +0000 kortney.hogan http://365daysofastronomy.org/?p=7683 Date: May 14, 2012 Title: Diamond Planet Finder Is A Star Podcaster: Michael Greenwell Links: http://michaelgreenwell.wordpress.com/ and http://exitstageright.wordpress.com/ Description: Last year, after making an enormously publicized discovery astronomer Matthew Bailes used his moment of fame to defend his scientific colleagues and to try to point us in the direction in which we need to be looking. I think he should be applauded for this and we would do well to listen to what he had to say. Bio: Michael Greenwell has worked, at various times, as a university tutor, a barman, a DJ (not a very good one), an office lackey, supermarket worker, president of a small charity, a researcher, a librarian, a volunteer worker in Nepal during the civil war there, and some other things that were too tedious to mention. He blogs here and also runs the animal extinction site Exit Stage Right. Today's Sponsor: "This episode of 365 days of Astronomy is sponsored by 'The Heliochromologist' " "This episode of 365 days of astronomy was sponsored by iTelescope.net - Expanding your horizons in astronomy today. The premier on-demand telescope network, at dark sky sites in Spain, New Mexico and Siding Spring, Australia." Transcript: At the end of last August, you probably read about the scientists who found a planet that is, in their words “certainly crystalline” or in other words, a large…. well… ok…a VERY large diamond…in fact, it is about 4 times the diameter of the Earth. The planet orbits a pulsar, which they referred to as Beyonce on account of the amount of Bling it was showing off. The story got a lot of coverage but one of the scientists involved, Matthew Bailes, did something a couple of weeks later that was rather brave and just as worthy of note - and I think that he should be applauded for it and that we would do well to listen to what he had to say. Specifically, he wrote an article for an Australian website called “The Conversation” in which he used the opportunity the extensive media coverage this discovery gave him to defend climate scientists and try to draw people’s attention to a problem that is ever worsening ie the fact that while the media are happy to report about weird weather on Jupiter or Saturn for example, they show a certain reluctance to talk about Global Weirding and the problems of Climate change here on planet Earth. I’ll quote to you now a slightly shortened version of what he said…

Following the publication of our finding in the journal Science, our research received amazing attention from the world’s media. I was asked by many journalists about the significance of the discovery. If I were honest, I’d have to concede that, although worthy of publication in Science, in the field of astrophysics it isn’t that significant. And yet the diamond planet has been hugely successful in igniting public curiosity about the universe in which we live. Imagine for a minute that, instead of discovering a diamond planet, we’d made a breakthrough in global temperature projections. Let’s say we studied computer models of the influence of excessive greenhouse gases, verified them through observations, then had them peer-reviewed and published in Science. Instead of sitting back and basking in the glory, I suspect we’d find a lot of commentators, many with no scientific qualifications, pouring scorn on our findings. People on the fringe of science would be quoted as opponents of our work, arguing that it was nothing more than a theory yet to be conclusively proven. Before long our credibility and findings would be under serious question. But luckily we’re not climate scientists. It may come as a big surprise to many, but there is actually no difference between how science works in astronomy and climate change – or any other scientific discipline for that matter. We make observations, run simulations, test and propose hypotheses, and undergo peer review of our findings. Of course we all make mistakes. But eventually the prevailing wisdom of the community triumphs and the field advances. It’s wonderful to be a part of that process. But on occasion those from the fringe of the scientific community will push a position that is simply not credible against the weight of evidence. This occurs within any discipline. But it seems it’s only in the field of climate science that such people are given airtime and column inches to espouse their views. Those who want to ignore what’s happening to Earth feel they need to be able to quote “alternative studies”, regardless of the scientific merit of those studies. In all fields of science, papers are challenged and statistics are debated. If there is any basis to these challenges they stand, but if not they fall by the wayside and the field continues to advance. When big theories fall, it isn’t because of business or political pressures – it’s because of the scientific process. Sadly, the same media commentators who celebrate diamond planets without question are all too quick to dismiss the latest peer-reviewed evidence that suggests man-made activities are responsible for changes in concentrations of CO2 in our atmosphere. The scientific method is universal. If we selectively ignore it in certain disciplines, we do so at our peril.

"Should the free precession be accepted as the correct explanation of the phenomena, it will give an important tool to study white dwarf equations of state. The theory of compact objects predicts certain relations between the spin and precession periods, and our finding provides a good test for the theory and establishes a qualitative model to be explored both theoretically and observationally. Detection of precession can become a powerful tool in searching for the internal properties of compact stars, which would be otherwise inaccessible for us. Combined with other methods to estimate masses and density of the WDs in CVs, the precession period will help to refine these values, which in turn, allows for testing and proving the theory for the precession of compact stars and may allow for further advances in our knowledge of the structure of WDs and the influence of accretion on them."

Some interesting things were also observed in the quiescent state prompting additional scrutiny during this year's season of the longer term behaviour of the system when at quiescence. It has been great to be a part of the wonderful science research that is still ongoing. Its all part of the great science you can do as a part of any number of citizen science initiatives. The AAVSO and Variable Stars South have many and varied research projects just like this one where you can play a significant part in gathering the data and working with professional astronomers. It was great working with such professional people ably lead by Vitaly and George Sjoberg. Participation in campaigns like this is a great way to get to know other astronomers, and build your credibility as a capable amateur astronomer. End of podcast: 365 Days of Astronomy ===================== The 365 Days of Astronomy Podcast is produced by the Astrosphere New Media Association. Audio post-production by Preston Gibson. Bandwidth donated by libsyn.com and wizzard media. Web design by Clockwork Active Media Systems. You may reproduce and distribute this audio for non-commercial purposes. Please consider supporting the podcast with a few dollars (or Euros!). Visit us on the web at 365DaysOfAstronomy.org or email us at info@365DaysOfAstronomy.org. Until tomorrow...goodbye.]]> http://365daysofastronomy.org/2012/05/10/may-10th-twinkle-twinkle-little-star-how-i-wonder-fs-aur/feed/ 0 podcast iya 365 Date: May 10, 2012 - Title: Twinkle Twinkle little star ...... How I wonder FS Aur? - Podcaster: Peter Lake - Organization: AARTScope Blog - Links: http://aartscope.blogspot.com http://vitaly.neustroev.net/research/observing-campaigns/ http://www. Date: May 10, 2012 Title: Twinkle Twinkle little star ...... How I wonder FS Aur? Podcaster: Peter Lake Organization: AARTScope Blog Links: http://aartscope.blogspot.com http://vitaly.neustroev.net/research/observing-campaigns/ http://www.twitter.com/fs_Aur http://www.aavso.org Description: FS Aur is one of the most strangest and erratic variable Stars. Peter Lake reports on the data collected as part of the broader work with Dr Vitaly Neustroev of the Oulu University Finland and discusses the past two seasons of observations. Peter Lake is an Amateur Astronomer from Melbourne Australia and regularly discusses how people can be involved in citizen science and observation programs. Bio: Peter Lake is an amateur Astronomer from Melbourne, Australia, a member of Variable Stars South and the AAVSO and he owns and operates a 0.5m Planewave CDK Telescope at New Mexico skies, which is affiliated to iTelescope.net. Peter has been a participant in citizen science and recovered asteroid 2000 EV70 during the Spacewatch FMO program. More recently Peter has been actively involved in the study of cataclysmic variable star FS Aur, and followup exoplanet observations on Kepler targets of interest. Sponsor: "This episode of 365 days of astronomy is sponsored with thanks to all non-US contributors for showing us that the night sky is something we can all share." "Additional sponsorship for this episode of 365 days of astronomy was provided by iTelescope.net - Expanding your horizons in astronomy today. The premier on-demand telescope network, at dark sky sites in Spain, New Mexico and Siding Spring, Australia." Transcript: Like duck hunting, Variable Stars have their "Seasons" also. A season being where the variable star in question is in the optimal position for "shooting with CCDs" ie observable for most of the night, during this time ideally it can be visible for as many as 6-7 hours per night. FS Aur is a Cataclysmic Variable is now low in the west at sunset at the close of an intensive second season. So I though it would be good to review these past two seasons, before once again, it comes around for observations in the next northern winter. FS Aur is one of the strangest and complex objects in the extensive variable star family. It is thought to be a magnetic white dwarf and red giant binary Star with a third object acting on it in a circumbinary orbit. (Tovmassian et al., 2010) Back in 2010 there was a sporadic and incomplete light curve and astronomers wanted answers. When they want answers they often leverage the collective effort of the American Association of Variable Star Observers (AAVSO), to muscle up some more observations and data. FS Aur has a number of photometric and spectroscopic cycles going on. On top of this it goes into outburst about every 12-15 days. The outburst duration is so short (2-3 days) it has been regularly missed in the past - so in the 2010/11 season Dr Neustroev rallied a special effort. For the first time, members of the AAVSO mapped the entire outburst cycle, a good number of times. Dr Vitaly Neustroev is the University Researcher (Yliopistotutkija) at the University of Oulu, Finland and he is a key researcher on FS Aur, working hard to better understand its erratic behaviour. Visit the observing campaign page here, and also follow on (Twitter). I like following Cataclysmic Variables, after catching Simostronomy fever, and I have been a regular on FS Aur since Dr Neustroev's call to action. During the campaign FS Aur has been dancing away with a little periodic wobble at about 15.9 with the odd subtle change in brightness, then it goes really dull to 16.2 then literally within 24-36 hours it pops up to magnitude about Mag 14. As an amateur astronomer I am always careful to point out that I'm not qualified to say how or why, but I can tell you when, where and how bright! So what is going on with FS Aur - Dr Neustroev describes it this way: 365 Days of Astronomy no May 9th: Astronomy Word of the Week: Nova http://365daysofastronomy.org/2012/05/09/may-9th-astronomy-word-of-the-week-nova/ http://365daysofastronomy.org/2012/05/09/may-9th-astronomy-word-of-the-week-nova/#comments Wed, 09 May 2012 11:00:09 +0000 kortney.hogan http://365daysofastronomy.org/?p=7650 Date: May 9, 2012 Title: Astronomy Word of the Week: Nova Podcaster: Dr. Christopher Crockett Organization: United States Naval Observatory Links: http://christophercrockett.com http://astrowow.wordpress.com/ Description: Why do once invisible stars suddenly flare up and then slowly fade from view? The astronomy word of the week is "nova". Bio: Dr. Christopher Crockett is an astronomer at the United States Naval Observatory in Flagstaff, Arizona. His research involves searching for planets around very young stars (“only” a few million years old). It is hoped that the results from this research will help constrain models of planet formation and lead to a better understanding of where, when, and how often planets form. Chris is also passionate about astronomy outreach and education and will talk for hours about the Universe if you let him. Sponsors: Sponsorship for this episode of "365 days of Astronomy" is donated anonymously and dedicated to the men and women of NASA who strive to turn science fiction into science reality. Additional sponsorship for this episode has been provided by iTelescope.net - Expanding your horizons in astronomy today. The premier on-demand telescope network, at dark sky sites in Spain, New Mexico and Siding Spring, Australia. Transcript: In 1572, Danish astronomer Tycho Brahe, along with observers around the world, noticed a new star in the constellation Casseiopeia. Rivaling Venus as the brightest object in the night sky after the Moon, the unexpected guest remained visible for nearly two years before fading from view. The appearance of a new star was nothing short of revolutionary; astronomers long agreed that the celestial sphere was unchanging. A transient star challenged this assumption and suggested that the heavens were perhaps more dynamic than originally thought. The celestial intruder came to be known as a "nova" - after Tycho Brahe's extensive manuscript on the phenomenon - where he referred to the object simply by the latin term for a new star: "stella nova". While no one could have known it at the time, the new star was actually not new at all but rather a very old star experiencing a cataclysmic event. Most of the stars in the sky are not singular, like our Sun, but rather members of binary star systems - two stars locked in orbit around one another. Of this pair, one star is often more massive than its companion and therefore burns through its nuclear fuel at a faster rate. The heavier star reaches the end of its life before its sibling. When it does, the star inflates to become a red giant and sheds its outer layers into space leaving behind the hot, dense stellar core. The naked core, known as a "white dwarf", continues to orbit its stellar neighbor while taking the next few billion years to passively cool from a white-hot 100,000 degrees. In the case of close binary pairs, the white dwarf can actually siphon matter off of its companion. The intermingled gravitational fields of the two stars builds a bridge of predominately hydrogen gas spanning the distance between them. Gas from the still active star flows through this gravitational funnel and spills on to the surface of the white dwarf. The mass of the white dwarf controls the rate of mass accretion; if the rate is high enough, then something quite spectacular can happen. White dwarfs are an example of a rather exotic type of matter that physicists call "degenerate". Most gasses expand when you heat them up: the increasing temperature causes the molecules to zip around faster which in turn increases the gas pressure. At extreme densities - like those seen in the cores of stars - the gas behaves rather peculiarly. The pressure is no longer a slave to temperature: turn up the heat and the gas does not expand. This counterintuitive behavior is crucial to what happens next on the white dwarf's surface. As hydrogen from the donor star comes crashing down, the crushing force of gravity compresses it into a degenerate state and the intense radiation heats the gas to many millions of degrees. But having now obtained the properties of a degenerate gas, the newly acquired hydrogen shell doesn't expand in response to the rapid heating, but holds its pressure steady. And now things get interesting. At temperatures exceeding 16 million degrees Celsius, conditions on the surface mimic those deep in the cores of stars and a thermonuclear explosion is the result. Hydrogen is rapidly fused into helium and the resulting release of energy blows the outer hydrogen shell off the surface of the white dwarf at speeds exceeding ten million kilometers per hour. In mere days, the white dwarf can increase its brightness by 100,000 times. It can then take months - or in some cases years - for the star to slowly fade from view. Our Milky Way Galaxy experiences several dozen novae each year, only about ten of which are visible from Earth. A few are even visible to the naked eye. The most recent nova to be seen without the aid of binoculars or telescopes did so in the constellation Scorpius, reaching its peak brightness on February 17, 2007. Even more rare are what astronomers call "recurrent nova". Once the white dwarf has blown the hydrogen shell into space, the gas can slowly start building up again. These are novae that flare up repeatedly, sometimes once a year, sometimes once every couple of decades. In our whole galaxy, only ten novae are known to be recurrent. In the centuries since the new star of 1572, astronomers have come to realize that the event which gave novae their name was not what we know now as a nova. Up until early in the 20th century, a nova referred to any rapid brightening of a star. But there are many reasons stars suddenly flare into view. What Tycho saw was actually something far more powerful - a type of, aptly named, supernova. The supernova of 1572 was not the result of a flash of hydrogen burning on a white dwarf shell, but rather was caused by the complete detonation of a white dwarf. By stealing gas from a nearby companion slowly enough, the progenitor of the supernova delayed a nova flash while gradually increasing its temperature and pressure and eventually igniting hydrogen fusion throughout the interior of the once dead stellar core. With out the counterbalancing force of the rest of the star to throttle these reactions, the now violently active core obliterated itself in one of the most powerful explosions the Universe can produce. The event of 1572 ushered in a new era of astronomy, one in which the constancy of the celestial sphere could no longer be assumed. Novae - and their more powerful supernovae cousins - are constant reminders that we, in fact, live in a highly dynamic and energetic Universe. End of podcast: 365 Days of Astronomy ===================== The 365 Days of Astronomy Podcast is produced by the Astrosphere New Media Association. Audio post-production by Preston Gibson. Bandwidth donated by libsyn.com and wizzard media. Web design by Clockwork Active Media Systems. You may reproduce and distribute this audio for non-commercial purposes. Please consider supporting the podcast with a few dollars (or Euros!). Visit us on the web at 365DaysOfAstronomy.org or email us at info@365DaysOfAstronomy.org. Until tomorrow...goodbye.]]> http://365daysofastronomy.org/2012/05/09/may-9th-astronomy-word-of-the-week-nova/feed/ 0 podcast iya 365 Date: May 9, 2012 - Title: Astronomy Word of the Week: Nova - Podcaster: Dr. Christopher Crockett - Organization: United States Naval Observatory - Links: http://christophercrockett.com http://astrowow.wordpress.com/ - Date: May 9, 2012 Title: Astronomy Word of the Week: Nova Podcaster: Dr. Christopher Crockett Organization: United States Naval Observatory Links: http://christophercrockett.com http://astrowow.wordpress.com/ Description: Why do once invisible stars suddenly flare up and then slowly fade from view? The astronomy word of the week is "nova". Bio: Dr. Christopher Crockett is an astronomer at the United States Naval Observatory in Flagstaff, Arizona. His research involves searching for planets around very young stars (“only” a few million years old). It is hoped that the results from this research will help constrain models of planet formation and lead to a better understanding of where, when, and how often planets form. Chris is also passionate about astronomy outreach and education and will talk for hours about the Universe if you let him. Sponsors: Sponsorship for this episode of "365 days of Astronomy" is donated anonymously and dedicated to the men and women of NASA who strive to turn science fiction into science reality. Additional sponsorship for this episode has been provided by iTelescope.net - Expanding your horizons in astronomy today. The premier on-demand telescope network, at dark sky sites in Spain, New Mexico and Siding Spring, Australia. Transcript: In 1572, Danish astronomer Tycho Brahe, along with observers around the world, noticed a new star in the constellation Casseiopeia. Rivaling Venus as the brightest object in the night sky after the Moon, the unexpected guest remained visible for nearly two years before fading from view. The appearance of a new star was nothing short of revolutionary; astronomers long agreed that the celestial sphere was unchanging. A transient star challenged this assumption and suggested that the heavens were perhaps more dynamic than originally thought. The celestial intruder came to be known as a "nova" - after Tycho Brahe's extensive manuscript on the phenomenon - where he referred to the object simply by the latin term for a new star: "stella nova". While no one could have known it at the time, the new star was actually not new at all but rather a very old star experiencing a cataclysmic event. Most of the stars in the sky are not singular, like our Sun, but rather members of binary star systems - two stars locked in orbit around one another. Of this pair, one star is often more massive than its companion and therefore burns through its nuclear fuel at a faster rate. The heavier star reaches the end of its life before its sibling. When it does, the star inflates to become a red giant and sheds its outer layers into space leaving behind the hot, dense stellar core. The naked core, known as a "white dwarf", continues to orbit its stellar neighbor while taking the next few billion years to passively cool from a white-hot 100,000 degrees. In the case of close binary pairs, the white dwarf can actually siphon matter off of its companion. The intermingled gravitational fields of the two stars builds a bridge of predominately hydrogen gas spanning the distance between them. Gas from the still active star flows through this gravitational funnel and spills on to the surface of the white dwarf. The mass of the white dwarf controls the rate of mass accretion; if the rate is high enough, then something quite spectacular can happen. White dwarfs are an example of a rather exotic type of matter that physicists call "degenerate". Most gasses expand when you heat them up: the increasing temperature causes the molecules to zip around faster which in turn increases the gas pressure. At extreme densities - like those seen in the cores of stars - the gas behaves rather peculiarly. The pressure is no longer a slave to temperature: turn up the heat and the gas does not expand. This counterintuitive behavior is crucial to what happens next on the white dwarf's surface. As hydrogen from the donor star comes crashing down, 365 Days of Astronomy no May 8th: What is Black http://365daysofastronomy.org/2012/05/08/may-8th-what-is-black/ http://365daysofastronomy.org/2012/05/08/may-8th-what-is-black/#comments Tue, 08 May 2012 11:00:41 +0000 kortney.hogan http://365daysofastronomy.org/?p=7646 Date: May 8, 2012 Title: What is Black Podcaster: Rob Sparks & Dr. Steven Pompea Organization: NOAO Links: www.noao.edu Description: Most people think of black as a color, but black is really the absence of light. Truly black surfaces reflect almost none of the light that falls on them. In this podcast, Dr. Stephen Pompea discusses black surface, how they are produced and why they are important in astronomy and other sciences. Bio: Rob Sparks is a science education specialist in the EPO group at NOAO and works on the Galileoscope project (www.galileoscope.org), providing design, dissemination and professional development. He also pens a great blog at halfastro.wordpress.com. Dr. Stephen Pompea did his undergraduate work in physics, space physics, and astronomy at Rice University, his Master’s work in physics teaching at Colorado State University, and his Ph.D. in astronomy at the University of Arizona. He is currently the manager of the Education and Public Outreach Group at the National Optical Astronomy Observatory. Sponsor: This episode of the 365 Days of Astronomy podcast is sponsored by the National Optical Astronomy Observatory. NOAO is a US national research and development center for ground-based nighttime astronomy. We provide astronomers access to world-class observing facilities on a peer-reviewed basis. Our mission is to engage in programs to develop the next generation of telescopes, instruments, and software tools necessary to enable exploration and investigation through the observable Universe. For information on observing proposals or our public programs, please visit www.noao.edu for more information. "This episode has also been sponsored by the Lake County Astronomical Society: Celebrating 30 years of stellar service to members and the public." Transcript: *** Transcript coming soon. *** End of podcast: 365 Days of Astronomy ===================== The 365 Days of Astronomy Podcast is produced by the Astrosphere New Media Association. Audio post-production by Preston Gibson. Bandwidth donated by libsyn.com and wizzard media. Web design by Clockwork Active Media Systems. You may reproduce and distribute this audio for non-commercial purposes. Please consider supporting the podcast with a few dollars (or Euros!). Visit us on the web at 365DaysOfAstronomy.org or email us at info@365DaysOfAstronomy.org. Until tomorrow...goodbye.]]> http://365daysofastronomy.org/2012/05/08/may-8th-what-is-black/feed/ 0 podcast iya 365 Date: May 8, 2012 - Title: What is Black - Podcaster: Rob Sparks & Dr. Steven Pompea - Organization: NOAO - Links: www.noao.edu - Description: Most people think of black as a color, but black is really the absence of light. Date: May 8, 2012 Title: What is Black Podcaster: Rob Sparks & Dr. Steven Pompea Organization: NOAO Links: www.noao.edu Description: Most people think of black as a color, but black is really the absence of light. Truly black surfaces reflect almost none of the light that falls on them. In this podcast, Dr. Stephen Pompea discusses black surface, how they are produced and why they are important in astronomy and other sciences. Bio: Rob Sparks is a science education specialist in the EPO group at NOAO and works on the Galileoscope project (www.galileoscope.org), providing design, dissemination and professional development. He also pens a great blog at halfastro.wordpress.com. Dr. Stephen Pompea did his undergraduate work in physics, space physics, and astronomy at Rice University, his Master’s work in physics teaching at Colorado State University, and his Ph.D. in astronomy at the University of Arizona. He is currently the manager of the Education and Public Outreach Group at the National Optical Astronomy Observatory. Sponsor: This episode of the 365 Days of Astronomy podcast is sponsored by the National Optical Astronomy Observatory. NOAO is a US national research and development center for ground-based nighttime astronomy. We provide astronomers access to world-class observing facilities on a peer-reviewed basis. Our mission is to engage in programs to develop the next generation of telescopes, instruments, and software tools necessary to enable exploration and investigation through the observable Universe. For information on observing proposals or our public programs, please visit www.noao.edu for more information. "This episode has also been sponsored by the Lake County Astronomical Society: Celebrating 30 years of stellar service to members and the public." Transcript: *** Transcript coming soon. *** End of podcast: 365 Days of Astronomy ===================== The 365 Days of Astronomy Podcast is produced by the Astrosphere New Media Association. Audio post-production by Preston Gibson. Bandwidth donated by libsyn.com and wizzard media. Web design by Clockwork Active Media Systems. You may reproduce and distribute this audio for non-commercial purposes. Please consider supporting the podcast with a few dollars (or Euros!). Visit us on the web at 365DaysOfAstronomy.org or email us at info@365DaysOfAstronomy.org. Until tomorrow...goodbye. 365 Days of Astronomy no May 7th: The Late Heavy Bombardment — an Extended Version? http://365daysofastronomy.org/2012/05/11/may-11th-take-mercury-for-a-spin/ http://365daysofastronomy.org/2012/05/11/may-11th-take-mercury-for-a-spin/#comments Fri, 11 May 2012 12:03:58 +0000 kortney.hogan http://365daysofastronomy.org/?p=7672 Date: May 11, 2012 Title: Take Mercury for a Spin Podcaster: Bob Hirshon Organization: American Association for the Advancement of Science (AAAS) Links: http://www.aaas.org Description: The Google Earth platform is useful for more than just checking out Earth-bound topography and features. AAAS Science Update host Bob Hirshon spoke with ace programmer Jason Smith, of Silicon Valet, about how he converts raw image data of the planet Mercury taken by the MESSENGER spacecraft into KML files that map the imagery onto the Google Earth sphere. The result? A detailed Mercury globe that anyone can take for a spin. Bio: Bob Hirshon is Senior Project Director at the American Association for the Advancement of Science (AAAS) and host of the daily radio show and podcast Science Update. Now in its 24th year, Science Update is heard on over 300 commercial stations nationwide. Hirshon also heads up Kinetic City, including the Peabody Award winning children’s radio drama, McGraw-Hill book series and Codie Award winning website and education program. He oversees the Science NetLinks project for K-12 science teachers, part of the Verizon Foundation Thinkfinity partnership. Hirshon is a Computerworld/ Smithsonian Hero for a New Millennium laureate. Sponsor: "This episode of 365 Days of Astronomy is sponsored by The Education and Outreach team for the MESSENGER mission to planet Mercury. Follow the mission as the spacecraft helps to unlock the secrets of the inner solar system at www.messenger-education.org" "Additional sponsorship for this episode of 365 days of astronomy was provided by iTelescope.net - Expanding your horizons in astronomy today. The premier on-demand telescope network, at dark sky sites in Spain, New Mexico and Siding Spring, Australia." Transcript: *** Transcript coming soon. *** End of podcast: 365 Days of Astronomy ===================== The 365 Days of Astronomy Podcast is produced by the Astrosphere New Media Association. Audio post-production by Preston Gibson. Bandwidth donated by libsyn.com and wizzard media. Web design by Clockwork Active Media Systems. You may reproduce and distribute this audio for non-commercial purposes. Please consider supporting the podcast with a few dollars (or Euros!). Visit us on the web at 365DaysOfAstronomy.org or email us at info@365DaysOfAstronomy.org. Until tomorrow...goodbye.]]> http://365daysofastronomy.org/2012/05/11/may-11th-take-mercury-for-a-spin/feed/ 0 podcast iya 365 Date: May 11, 2012 - Title: Take Mercury for a Spin - Podcaster: Bob Hirshon - Organization: American Association for the Advancement of Science (AAAS) - Links: http://www.aaas.org - Description: The Google Earth platform is useful for more than ... Date: May 11, 2012 Title: Take Mercury for a Spin Podcaster: Bob Hirshon Organization: American Association for the Advancement of Science (AAAS) Links: http://www.aaas.org Description: The Google Earth platform is useful for more than just checking out Earth-bound topography and features. AAAS Science Update host Bob Hirshon spoke with ace programmer Jason Smith, of Silicon Valet, about how he converts raw image data of the planet Mercury taken by the MESSENGER spacecraft into KML files that map the imagery onto the Google Earth sphere. The result? A detailed Mercury globe that anyone can take for a spin. Bio: Bob Hirshon is Senior Project Director at the American Association for the Advancement of Science (AAAS) and host of the daily radio show and podcast Science Update. Now in its 24th year, Science Update is heard on over 300 commercial stations nationwide. Hirshon also heads up Kinetic City, including the Peabody Award winning children’s radio drama, McGraw-Hill book series and Codie Award winning website and education program. He oversees the Science NetLinks project for K-12 science teachers, part of the Verizon Foundation Thinkfinity partnership. Hirshon is a Computerworld/ Smithsonian Hero for a New Millennium laureate. Sponsor: "This episode of 365 Days of Astronomy is sponsored by The Education and Outreach team for the MESSENGER mission to planet Mercury. Follow the mission as the spacecraft helps to unlock the secrets of the inner solar system at www.messenger-education.org" "Additional sponsorship for this episode of 365 days of astronomy was provided by iTelescope.net - Expanding your horizons in astronomy today. The premier on-demand telescope network, at dark sky sites in Spain, New Mexico and Siding Spring, Australia." Transcript: *** Transcript coming soon. *** End of podcast: 365 Days of Astronomy ===================== The 365 Days of Astronomy Podcast is produced by the Astrosphere New Media Association. Audio post-production by Preston Gibson. Bandwidth donated by libsyn.com and wizzard media. Web design by Clockwork Active Media Systems. You may reproduce and distribute this audio for non-commercial purposes. Please consider supporting the podcast with a few dollars (or Euros!). Visit us on the web at 365DaysOfAstronomy.org or email us at info@365DaysOfAstronomy.org. Until tomorrow...goodbye. 365 Days of Astronomy no 365 Days of Astronomy http://365daysofastronomy.org An astronomy podcast every day, all year Wed, 16 May 2012 11:00:41 +0000 en hourly 1 http://wordpress.org/?v=3.1 An astronomy podcast every day, all year 365 Days of Astronomy no An astronomy podcast every day, all year 365 Days of Astronomy http://365daysofastronomy.org/wp-content/plugins/powerpress/rss_default.jpg http://365daysofastronomy.org May 16th: GPS http://365daysofastronomy.org/2012/05/16/may-16th-gps/ http://365daysofastronomy.org/2012/05/16/may-16th-gps/#comments Wed, 16 May 2012 11:00:41 +0000 kortney.hogan http://365daysofastronomy.org/?p=7689 Date: May 16, 2012 Title: GPS Podcaster: Steve Nerlich Organization: Cheap Astronomy Links: www.cheapastro.com Description: Cheap Astronomy once again demonstrates that pretty much everything in life has a connection to astronomy. Bio: Cheap Astronomy offers an educational website because in space no-one can hear you podcast. Today's Sponsor: "This episode of 365 days of Astronomy" is sponsored by the Lake County Astronomical Society: Celebrating 30 years of stellar service to members and the public." Additional sponsorship for this episode has also been provided by iTelescope.net - Expanding your horizons in astronomy today. The premier on-demand telescope network, at dark sky sites in Spain, New Mexico and Siding Spring, Australia. Transcript: Hi this is Steve Nerlich from Cheap Astronomy www.cheapastro.com and this is GPS OK – If you don’t have one, you know someone who does, so let’s skip the introductions and get straight down to the astronomy. A standard GPS configuration is a constellation of 24 GPS satellites. The satellites are all at an altitude of 20,200 km with an orbital period of 11 hours and 58 minutes – which means they do exactly 2 orbits for each time the Earth spins once on its axis. Four satellites each follow six orbital planes separated by 60 degrees which surround the Earth in an (airquotes) ‘birdcage’ of criss-crossing orbits. There a link to the relevant Wikipedia article from the Cheap Astronomy podcast page which has a nice animation of a GPS satellite constellation. At last count, there were actually 31 actively transmitting GPS satellites – with these extra number increasing location accuracy and redundancy. There’s been some recent media regarding a growing risk of dropping below the minimum 24 active satellites required to make GPS work effectively, but it remains to be seen if this risk will be realised in the face of the increasing economic importance of maintaining a working GPS system. A GPS satellite broadcasts a signal indicating where it is and the time the signal was broadcast – your receiver then determines, from the time it receives that signal, the distance travelled by the signal, knowing that, being a radio transmission, the signal travels at the speed of light. By making just four calculations from four satellites in the sky, your GPS receiver can then establish its position with respect to latitude, longitude and altitude. It’s all about the conjunction of spheres. Imagine one satellite broadcasting a radio signal. If you pick up that signal and determine it’s a 100 km away, all you really know is that you are somewhere on a surface of a sphere with a 100 km radius that has the satellite at its centre. If there’s two such satellites then you’ll know you are somewhere on the circumference of a circle representing the plane where the two spheres of radio broadcast overlap. Introduce a third satellite and you can narrow down your location to just two points in space which are the points where two differently orientated circle circumferences intersect. Potentially this may be enough to roughly determine your position since you can anticipate you will be on the one of those two points corresponding to the surface of the Earth. But for strictest accuracy – including accuracy in determining your altitude above sea level, the signal from a fourth satellite is required. And that is the idea of the constellation of GPS satellites. Keeping 24 satellites moving in the same orbit, tracing a birdcage of divergent paths around the globe ensures there will always be four satellites in the sky wherever you happen to be on Earth. Now when I say GPS satellites just have to broadcast where they are – actually knowing where they are is a whole separate operation, While the orbital period is predictable, knowing at what point they are on that orbit requires some very accurate time keeping – for which reason each satellite has an atomic clock. Nonetheless, even this isn’t enough, as the orbital paths of the satellites are subject to slight shifting due to the gravitational influence of the Sun and the Moon. To keep track of these changes the satellites are monitored from a fixed, known location on the Earth’s surface – a function currently managed by the 50th Space Wing of the US Airforce Space Command – seriously. Now, given that your GPS receiver is working out its distance from each of four satellites based solely on the time lag of a signal moving at the speed of light from a satellite just over 20,000 kilometres away – there is considerable potential for a margin of error that could see you driving over the embankment into a river when that sexy voice says ‘turn left now’. There are a range of methods to deal with various sources of error. Firstly your GPS receiver carries an electronic almanac of which satellite should be where since confusion can arise when the satellite radio signals get reflected off surroundings, such as tall buildings. This electronic almanac is constructed from calibration data received from the GPS satellites, although these data are generally relayed from a ground-based source – such as Airforce Space Command. The almanac helps your receiver distinguish between garbage signals and genuine GPS signals. The receiver also receives time checks from the satellites since, most GPS receivers determine time from a cheap (not that there’s anything wrong with that) quartz clock rather than the ultra-accurate atomic clocks of the satellites. Clock error is probably the biggest potential source of GPS error, which is why, even though you could almost get away with determining your position from just 3 satellites, it is the fourth reading (which we might call quadrangulation) that ensures the poorer accuracy of the GPS receiver’s clock is effectively accounted for. Interestingly, there’s also relativistic effects to account for, since the satellites move in a weaker gravity field (meaning by general relativity their clocks run faster), and they also move at speed relative to the surface of the Earth (meaning by special relativity their clocks run slower). It turns out that the nett effect is that the satellites’ clocks run about 38 microseconds per day faster than they would at the Earth’s surface. To account for this, the clocks are actually set to run at a slightly lower rate, to keep pace with clocks running on the Earth’s surface. In the world of atomic clocks, various time keeping callibrations are also required to account for changes in the rotation of the Earth – which is influenced by the tidal drag of the Moon , the inertia of the Earth’s molten interior and even the melting of glaciers. Overall, the Earth’s rotation is slowing, leading to a lengthening of a solar day. Consequently a leap second must be introduced to atomic timepieces which measure Universal Coordinated Time (known as UTC – because of the French). In fact, a leap second is required to be added to UTC every 18 months or so because each year (on average) the length of a solar day increases by about 0.002 seconds. The atomic clocks of GPS satellites were aligned to UTC in 1980 – but as of 2009, these atomic clocks in orbit now vary by 19 seconds and to keep it simple we just say they are running at GPS time. Various under-the-hood adjustments are made along the way so that your GPS receiver can tell you the local time wherever you happen to be – as well as telling you where you are of course to within… well, within 10 metres is the general benchmark, although this takes a few minutes to establish after the unit is turned on and the accuracy will degrade with tall trees or buildings around. So, you know, it’s a guide – not an absolute – it’s still a good idea to keep one eye on the road. Thanks for listening. This is Steve Nerlich from Cheap Astronomy, www.cheapastro.com. Cheap Astronomy offers an educational website where you can’t put a price on space. No ads, no profit, just good science. Bye. End of podcast: 365 Days of Astronomy ===================== The 365 Days of Astronomy Podcast is produced by the New Media Working Group of the International Year of Astronomy 2009. Audio post-production by Preston Gibson. Bandwidth donated by libsyn.com and wizzard media. Web design by Clockwork Active Media Systems. You may reproduce and distribute this audio for non-commercial purposes. Please consider supporting the podcast with a few dollars (or Euros!). Visit us on the web at 365DaysOfAstronomy.org or email us at info@365DaysOfAstronomy.org. Until tomorrow...goodbye.]]> http://365daysofastronomy.org/2012/05/16/may-16th-gps/feed/ 0 podcast iya 365 Date: May 16, 2012 - Title: GPS Podcaster: Steve Nerlich - Organization: Cheap Astronomy - Links: www.cheapastro.com - Description: Cheap Astronomy once again demonstrates that pretty much everything in life has a connection to astronomy. - Date: May 16, 2012 Title: GPS Podcaster: Steve Nerlich Organization: Cheap Astronomy Links: www.cheapastro.com Description: Cheap Astronomy once again demonstrates that pretty much everything in life has a connection to astronomy. B... 365 Days of Astronomy no May 15th: Astronomy Word of the Week: Obliquity http://365daysofastronomy.org/2012/05/15/may-15th-astronomy-word-of-the-week-obliquity/ http://365daysofastronomy.org/2012/05/15/may-15th-astronomy-word-of-the-week-obliquity/#comments Tue, 15 May 2012 11:00:14 +0000 kortney.hogan http://365daysofastronomy.org/?p=7687 Date: May 15, 2012 Title: Astronomy Word of the Week: Obliquity Podcaster: Dr. Christopher Crockett Organization: United States Naval Observatory Links: http://christophercrockett.com http://astrowow.wordpress.com/ Description: The tilt of our planet is about much more than the seasons. The astronomy word of the week is "obliquity". Bio: Dr. Christopher Crockett is an astronomer at the United States Naval Observatory in Flagstaff, Arizona. His research involves searching for planets around very young stars (“only” a few million years old). It is hoped that the results from this research will help constrain models of planet formation and lead to a better understanding of where, when, and how often planets form. Chris is also passionate about astronomy outreach and education and will talk for hours about the Universe if you let him. Today's Sponsor: "This episode of 365 days of Astronomy" is sponsored by iTelescope.net - Expanding your horizons in astronomy today. The premier on-demand telescope network, at dark sky sites in Spain, New Mexico and Siding Spring, Australia. This episode has also been sponsored by Lake County Astronomical Society: Celebrating 30 years of stellar service to members and the public. Transcript: The planet you're standing on is not very steady. She bobs and wobbles, ducks and weaves, as she makes her annual trek around the Sun. Our home constantly struggles with forces both external and internal; the Sun, the Moon, and the planets tug her back and forth while shifting masses within force her to constantly find new balance. The tilt of our planet's axis - what astronomers call its obliquity - is one measure of this interplanetary tug-of-war. Obliquity measures how far over a planet or moon is tipped relative to its orbit; in the Earth's case, it's about 23 degrees. We feel the obliquity in the changing seasons. In June, the north pole is tipped towards the Sun. The northern hemisphere experiences longer days and more direct sunlight giving us warm summer days. In December, the north pole is tipped away from the Sun and everyone above the equator experiences the bitter chill of winter as the days get shorter and the sunlight reaches us more obliquely. The other planets in our solar system exhibit a wide range of obliquities. Mars, Saturn, and Neptune are all tipped by roughly the same amount as Earth. Mercury and Jupiter have hardly any obliquity at all - which means no seasons for them. Venus' obliquity is 177 degrees; it is almost completely upside down. Put another way, it rotates in the opposite direction from Earth. Were there ever to be a break in Venus' stifling cloud layer, native Venusians would see the Sun rise in the west and set in the east! Uranus is another strange character; his obliquity is 97 degrees. Uranus is lying on his side! This leads to some very strange days and seasons. Each pole of Uranus alternates between being in constant sunlight for 42 years, then perpetual darkness for another 42 years. Only a very thin strip along the equator experiences anything like day/night cycles that we experience - and even then the Sun is frequently sitting very low on the horizon. Astronomers aren't entirely certain how Venus and Uranus came to have such extreme obliquities. A leading hypothesis is that both experienced massive collisions at some point in their distant past, essentially knocking them over. A glancing blow from a minor planet isn't the only thing that can change an obliquity. The tilt of our planet's axis is drifting - ever so slightly - all the time. The poles actually trace out a rather complex dance over time scales ranging from minutes to thousands of centuries. Like a spinning top, our planet also wobbles - though it does so very slowly. Over a period of 26,000 years, the poles trace out a giant circle in the sky. Right now, the north pole points pretty close to the star Polaris. But over time that will change, and in some epochs it will be pointing at nothing at all. This wobble - or precession - doesn't change the amount of obliquity; it simply changes where in space the poles are pointing. The Moon, however, does tug on our planet's axis. In addition to rotation and precession, the Earth experiences something called nutation. This is a slight rocking of the Earth's axis caused by the changing positions of the Moon, the Sun, and all the other bodies in the solar system. With many players involved, the motion from nutation is fairly complex. The main component nods the planet by a couple hundred meters over a nearly 19 year cycle that is tied to how the Moon's orbit drifts around the Earth. Our planet also has to contend with forces much closer to home. Internal motions of magma, deep sea currents, changing ocean salinity, winds, melting ice sheets, and even earthquakes all conspire to constantly change the distribution of mass within the Earth. The planet responds by continuously shifting its spin axis - an effect known as polar motion. This is a bit different than nutation; it actually changes where on Earth the north and south poles are located. Hard as it may be to fathom, these are not fixed locations on the globe. The drift is very small - centimeters per year - but it does add a complex twist to understanding our planets motion in space. The presence of a large moon is believed to help stabilize our obliquity. The tilt does change by a few degrees over many millions of years, but manages to hold steady at around 20-25 degrees. Mars, conversely, appears to be going through a chaotic evolution in its obliquity. Computer simulations of its stability suggest that, over the past few million years, the Red Planet's tilt has oscillated wildly between zero and sixty degrees which may lead to drastic swings in the environment. Many astrobiologists - scientists who study the evolution and origin of life in a cosmic context - argue that our moon may be an essential ingredient for providing a stable environment within which life could thrive. Does this mean that the existence of complex life and advanced civilizations is dependent on the presence of a large satellite? That's hard to say. It is certainly plausible that our closest neighbor in space has been an indispensable partner in the evolution of our species. I'm continually amazed at how a simple concept - like the tilt of a planet - can actually lead down a labyrinthian path of subtleties. Studying Earth's obliquity, and the obliquity of all the other planets and moons, reveals much about the dynamics of our planet, the interplay of our home and neighboring worlds, and even the often times cataclysmic evolution of the solar system. While the subtleties are far removed from our day-to-day lives, our Earth's position in space actually is inseparable from the human experience. The June solstice is just over a month away. Whether you're bundling up for winter, or heading to the beach for summer, remember: the Earth's obliquity is the reason for the seasons! End of podcast: 365 Days of Astronomy ===================== The 365 Days of Astronomy Podcast is produced by the New Media Working Group of the International Year of Astronomy 2009. Audio post-production by Preston Gibson. Bandwidth donated by libsyn.com and wizzard media. Web design by Clockwork Active Media Systems. You may reproduce and distribute this audio for non-commercial purposes. Please consider supporting the podcast with a few dollars (or Euros!). Visit us on the web at 365DaysOfAstronomy.org or email us at info@365DaysOfAstronomy.org. Until tomorrow...goodbye.]]> http://365daysofastronomy.org/2012/05/15/may-15th-astronomy-word-of-the-week-obliquity/feed/ 0 podcast iya 365 Date: May 15, 2012 - Title: Astronomy Word of the Week: Obliquity Podcaster: Dr. Christopher Crockett - Organization: United States Naval Observatory - Links: http://christophercrockett.com http://astrowow.wordpress.com/ - Date: May 15, 2012 Title: Astronomy Word of the Week: Obliquity Podcaster: Dr. Christopher Crockett Organization: United States Naval Observatory Links: http://christophercrockett.com http://astrowow.wordpress.com/ Description: The tilt of our planet is about much more than the seasons. The astronomy word of the week is "obliquity". Bio: Dr. Christopher Crockett is an astronomer at the United States Naval Observatory in Flagstaff, Arizona. His research involves searching for planets around very young stars (“only” a few million years old). It is hoped that the results from this research will help constrain models of planet formation and lead to a better understanding of where, when, and how often planets form. Chris is also passionate about astronomy outreach and education and will talk for hours about the Universe if you let him. Today's Sponsor: "This episode of 365 days of Astronomy" is sponsored by iTelescope.net - Expanding your horizons in astronomy today. The premier on-demand telescope network, at dark sky sites in Spain, New Mexico and Siding Spring, Australia. This episode has also been sponsored by Lake County Astronomical Society: Celebrating 30 years of stellar service to members and the public. Transcript: The planet you're standing on is not very steady. She bobs and wobbles, ducks and weaves, as she makes her annual trek around the Sun. Our home constantly struggles with forces both external and internal; the Sun, the Moon, and the planets tug her back and forth while shifting masses within force her to constantly find new balance. The tilt of our planet's axis - what astronomers call its obliquity - is one measure of this interplanetary tug-of-war. Obliquity measures how far over a planet or moon is tipped relative to its orbit; in the Earth's case, it's about 23 degrees. We feel the obliquity in the changing seasons. In June, the north pole is tipped towards the Sun. The northern hemisphere experiences longer days and more direct sunlight giving us warm summer days. In December, the north pole is tipped away from the Sun and everyone above the equator experiences the bitter chill of winter as the days get shorter and the sunlight reaches us more obliquely. The other planets in our solar system exhibit a wide range of obliquities. Mars, Saturn, and Neptune are all tipped by roughly the same amount as Earth. Mercury and Jupiter have hardly any obliquity at all - which means no seasons for them. Venus' obliquity is 177 degrees; it is almost completely upside down. Put another way, it rotates in the opposite direction from Earth. Were there ever to be a break in Venus' stifling cloud layer, native Venusians would see the Sun rise in the west and set in the east! Uranus is another strange character; his obliquity is 97 degrees. Uranus is lying on his side! This leads to some very strange days and seasons. Each pole of Uranus alternates between being in constant sunlight for 42 years, then perpetual darkness for another 42 years. Only a very thin strip along the equator experiences anything like day/night cycles that we experience - and even then the Sun is frequently sitting very low on the horizon. Astronomers aren't entirely certain how Venus and Uranus came to have such extreme obliquities. A leading hypothesis is that both experienced massive collisions at some point in their distant past, essentially knocking them over. A glancing blow from a minor planet isn't the only thing that can change an obliquity. The tilt of our planet's axis is drifting - ever so slightly - all the time. The poles actually trace out a rather complex dance over time scales ranging from minutes to thousands of centuries. Like a spinning top, our planet also wobbles - though it does so very slowly. Over a period of 26,000 years, the poles trace out a giant circle in the sky. Right now, the north pole points pretty close to the star Polaris. 365 Days of Astronomy no May 14th: Diamond Planet Finder Is A Star http://365daysofastronomy.org/2012/05/14/may-14th-diamond-planet-finder-is-a-star/ http://365daysofastronomy.org/2012/05/14/may-14th-diamond-planet-finder-is-a-star/#comments Mon, 14 May 2012 11:00:46 +0000 kortney.hogan http://365daysofastronomy.org/?p=7683 Date: May 14, 2012 Title: Diamond Planet Finder Is A Star Podcaster: Michael Greenwell Links: http://michaelgreenwell.wordpress.com/ and http://exitstageright.wordpress.com/ Description: Last year, after making an enormously publicized discovery astronomer Matthew Bailes used his moment of fame to defend his scientific colleagues and to try to point us in the direction in which we need to be looking. I think he should be applauded for this and we would do well to listen to what he had to say. Bio: Michael Greenwell has worked, at various times, as a university tutor, a barman, a DJ (not a very good one), an office lackey, supermarket worker, president of a small charity, a researcher, a librarian, a volunteer worker in Nepal during the civil war there, and some other things that were too tedious to mention. He blogs here and also runs the animal extinction site Exit Stage Right. Today's Sponsor: "This episode of 365 days of Astronomy is sponsored by 'The Heliochromologist' " "This episode of 365 days of astronomy was sponsored by iTelescope.net - Expanding your horizons in astronomy today. The premier on-demand telescope network, at dark sky sites in Spain, New Mexico and Siding Spring, Australia." Transcript: At the end of last August, you probably read about the scientists who found a planet that is, in their words “certainly crystalline” or in other words, a large…. well… ok…a VERY large diamond…in fact, it is about 4 times the diameter of the Earth. The planet orbits a pulsar, which they referred to as Beyonce on account of the amount of Bling it was showing off. The story got a lot of coverage but one of the scientists involved, Matthew Bailes, did something a couple of weeks later that was rather brave and just as worthy of note - and I think that he should be applauded for it and that we would do well to listen to what he had to say. Specifically, he wrote an article for an Australian website called “The Conversation” in which he used the opportunity the extensive media coverage this discovery gave him to defend climate scientists and try to draw people’s attention to a problem that is ever worsening ie the fact that while the media are happy to report about weird weather on Jupiter or Saturn for example, they show a certain reluctance to talk about Global Weirding and the problems of Climate change here on planet Earth. I’ll quote to you now a slightly shortened version of what he said…

Following the publication of our finding in the journal Science, our research received amazing attention from the world’s media. I was asked by many journalists about the significance of the discovery. If I were honest, I’d have to concede that, although worthy of publication in Science, in the field of astrophysics it isn’t that significant. And yet the diamond planet has been hugely successful in igniting public curiosity about the universe in which we live. Imagine for a minute that, instead of discovering a diamond planet, we’d made a breakthrough in global temperature projections. Let’s say we studied computer models of the influence of excessive greenhouse gases, verified them through observations, then had them peer-reviewed and published in Science. Instead of sitting back and basking in the glory, I suspect we’d find a lot of commentators, many with no scientific qualifications, pouring scorn on our findings. People on the fringe of science would be quoted as opponents of our work, arguing that it was nothing more than a theory yet to be conclusively proven. Before long our credibility and findings would be under serious question. But luckily we’re not climate scientists. It may come as a big surprise to many, but there is actually no difference between how science works in astronomy and climate change – or any other scientific discipline for that matter. We make observations, run simulations, test and propose hypotheses, and undergo peer review of our findings. Of course we all make mistakes. But eventually the prevailing wisdom of the community triumphs and the field advances. It’s wonderful to be a part of that process. But on occasion those from the fringe of the scientific community will push a position that is simply not credible against the weight of evidence. This occurs within any discipline. But it seems it’s only in the field of climate science that such people are given airtime and column inches to espouse their views. Those who want to ignore what’s happening to Earth feel they need to be able to quote “alternative studies”, regardless of the scientific merit of those studies. In all fields of science, papers are challenged and statistics are debated. If there is any basis to these challenges they stand, but if not they fall by the wayside and the field continues to advance. When big theories fall, it isn’t because of business or political pressures – it’s because of the scientific process. Sadly, the same media commentators who celebrate diamond planets without question are all too quick to dismiss the latest peer-reviewed evidence that suggests man-made activities are responsible for changes in concentrations of CO2 in our atmosphere. The scientific method is universal. If we selectively ignore it in certain disciplines, we do so at our peril.

"Should the free precession be accepted as the correct explanation of the phenomena, it will give an important tool to study white dwarf equations of state. The theory of compact objects predicts certain relations between the spin and precession periods, and our finding provides a good test for the theory and establishes a qualitative model to be explored both theoretically and observationally. Detection of precession can become a powerful tool in searching for the internal properties of compact stars, which would be otherwise inaccessible for us. Combined with other methods to estimate masses and density of the WDs in CVs, the precession period will help to refine these values, which in turn, allows for testing and proving the theory for the precession of compact stars and may allow for further advances in our knowledge of the structure of WDs and the influence of accretion on them."

Following the publication of our finding in the journal Science, our research received amazing attention from the world’s media. I was asked by many journalists about the significance of the discovery. If I were honest, I’d have to concede that, although worthy of publication in Science, in the field of astrophysics it isn’t that significant. And yet the diamond planet has been hugely successful in igniting public curiosity about the universe in which we live. Imagine for a minute that, instead of discovering a diamond planet, we’d made a breakthrough in global temperature projections. Let’s say we studied computer models of the influence of excessive greenhouse gases, verified them through observations, then had them peer-reviewed and published in Science. Instead of sitting back and basking in the glory, I suspect we’d find a lot of commentators, many with no scientific qualifications, pouring scorn on our findings. People on the fringe of science would be quoted as opponents of our work, arguing that it was nothing more than a theory yet to be conclusively proven. Before long our credibility and findings would be under serious question. But luckily we’re not climate scientists. It may come as a big surprise to many, but there is actually no difference between how science works in astronomy and climate change – or any other scientific discipline for that matter. We make observations, run simulations, test and propose hypotheses, and undergo peer review of our findings. Of course we all make mistakes. But eventually the prevailing wisdom of the community triumphs and the field advances. It’s wonderful to be a part of that process. But on occasion those from the fringe of the scientific community will push a position that is simply not credible against the weight of evidence. This occurs within any discipline. But it seems it’s only in the field of climate science that such people are given airtime and column inches to espouse their views. Those who want to ignore what’s happening to Earth feel they need to be able to quote “alternative studies”, regardless of the scientific merit of those studies. In all fields of science, papers are challenged and statistics are debated. If there is any basis to these challenges they stand, but if not they fall by the wayside and the field continues to advance. When big theories fall, it isn’t because of business or political pressures – it’s because of the scientific process. Sadly, the same media commentators who celebrate diamond planets without question are all too quick to dismiss the latest peer-reviewed evidence that suggests man-made activities are responsible for changes in concentrations of CO2 in our atmosphere. The scientific method is universal. If we selectively ignore it in certain disciplines, we do so at our peril.

"Should the free precession be accepted as the correct explanation of the phenomena, it will give an important tool to study white dwarf equations of state. The theory of compact objects predicts certain relations between the spin and precession periods, and our finding provides a good test for the theory and establishes a qualitative model to be explored both theoretically and observationally. Detection of precession can become a powerful tool in searching for the internal properties of compact stars, which would be otherwise inaccessible for us. Combined with other methods to estimate masses and density of the WDs in CVs, the precession period will help to refine these values, which in turn, allows for testing and proving the theory for the precession of compact stars and may allow for further advances in our knowledge of the structure of WDs and the influence of accretion on them."

Some interesting things were also observed in the quiescent state prompting additional scrutiny during this year's season of the longer term behaviour of the system when at quiescence. It has been great to be a part of the wonderful science research that is still ongoing. Its all part of the great science you can do as a part of any number of citizen science initiatives. The AAVSO and Variable Stars South have many and varied research projects just like this one where you can play a significant part in gathering the data and working with professional astronomers. It was great working with such professional people ably lead by Vitaly and George Sjoberg. Participation in campaigns like this is a great way to get to know other astronomers, and build your credibility as a capable amateur astronomer. End of podcast: 365 Days of Astronomy ===================== The 365 Days of Astronomy Podcast is produced by the Astrosphere New Media Association. Audio post-production by Preston Gibson. Bandwidth donated by libsyn.com and wizzard media. Web design by Clockwork Active Media Systems. You may reproduce and distribute this audio for non-commercial purposes. Please consider supporting the podcast with a few dollars (or Euros!). Visit us on the web at 365DaysOfAstronomy.org or email us at info@365DaysOfAstronomy.org. Until tomorrow...goodbye.]]> http://365daysofastronomy.org/2012/05/10/may-10th-twinkle-twinkle-little-star-how-i-wonder-fs-aur/feed/ 0 podcast iya 365 Date: May 10, 2012 - Title: Twinkle Twinkle little star ...... How I wonder FS Aur? - Podcaster: Peter Lake - Organization: AARTScope Blog - Links: http://aartscope.blogspot.com http://vitaly.neustroev.net/research/observing-campaigns/ http://www. Date: May 10, 2012 Title: Twinkle Twinkle little star ...... How I wonder FS Aur? Podcaster: Peter Lake Organization: AARTScope Blog Links: http://aartscope.blogspot.com http://vitaly.neustroev.net/research/observing-campaigns/ http://www.twitter.com/fs_Aur http://www.aavso.org Description: FS Aur is one of the most strangest and erratic variable Stars. Peter Lake reports on the data collected as part of the broader work with Dr Vitaly Neustroev of the Oulu University Finland and discusses the past two seasons of observations. Peter Lake is an Amateur Astronomer from Melbourne Australia and regularly discusses how people can be involved in citizen science and observation programs. Bio: Peter Lake is an amateur Astronomer from Melbourne, Australia, a member of Variable Stars South and the AAVSO and he owns and operates a 0.5m Planewave CDK Telescope at New Mexico skies, which is affiliated to iTelescope.net. Peter has been a participant in citizen science and recovered asteroid 2000 EV70 during the Spacewatch FMO program. More recently Peter has been actively involved in the study of cataclysmic variable star FS Aur, and followup exoplanet observations on Kepler targets of interest. Sponsor: "This episode of 365 days of astronomy is sponsored with thanks to all non-US contributors for showing us that the night sky is something we can all share." "Additional sponsorship for this episode of 365 days of astronomy was provided by iTelescope.net - Expanding your horizons in astronomy today. The premier on-demand telescope network, at dark sky sites in Spain, New Mexico and Siding Spring, Australia." Transcript: Like duck hunting, Variable Stars have their "Seasons" also. A season being where the variable star in question is in the optimal position for "shooting with CCDs" ie observable for most of the night, during this time ideally it can be visible for as many as 6-7 hours per night. FS Aur is a Cataclysmic Variable is now low in the west at sunset at the close of an intensive second season. So I though it would be good to review these past two seasons, before once again, it comes around for observations in the next northern winter. FS Aur is one of the strangest and complex objects in the extensive variable star family. It is thought to be a magnetic white dwarf and red giant binary Star with a third object acting on it in a circumbinary orbit. (Tovmassian et al., 2010) Back in 2010 there was a sporadic and incomplete light curve and astronomers wanted answers. When they want answers they often leverage the collective effort of the American Association of Variable Star Observers (AAVSO), to muscle up some more observations and data. FS Aur has a number of photometric and spectroscopic cycles going on. On top of this it goes into outburst about every 12-15 days. The outburst duration is so short (2-3 days) it has been regularly missed in the past - so in the 2010/11 season Dr Neustroev rallied a special effort. For the first time, members of the AAVSO mapped the entire outburst cycle, a good number of times. Dr Vitaly Neustroev is the University Researcher (Yliopistotutkija) at the University of Oulu, Finland and he is a key researcher on FS Aur, working hard to better understand its erratic behaviour. Visit the observing campaign page here, and also follow on (Twitter). I like following Cataclysmic Variables, after catching Simostronomy fever, and I have been a regular on FS Aur since Dr Neustroev's call to action. During the campaign FS Aur has been dancing away with a little periodic wobble at about 15.9 with the odd subtle change in brightness, then it goes really dull to 16.2 then literally within 24-36 hours it pops up to magnitude about Mag 14. As an amateur astronomer I am always careful to point out that I'm not qualified to say how or why, but I can tell you when, where and how bright! So what is going on with FS Aur - Dr Neustroev describes it this way: 365 Days of Astronomy no May 9th: Astronomy Word of the Week: Nova http://365daysofastronomy.org/2012/05/09/may-9th-astronomy-word-of-the-week-nova/ http://365daysofastronomy.org/2012/05/09/may-9th-astronomy-word-of-the-week-nova/#comments Wed, 09 May 2012 11:00:09 +0000 kortney.hogan http://365daysofastronomy.org/?p=7650 Date: May 9, 2012 Title: Astronomy Word of the Week: Nova Podcaster: Dr. Christopher Crockett Organization: United States Naval Observatory Links: http://christophercrockett.com http://astrowow.wordpress.com/ Description: Why do once invisible stars suddenly flare up and then slowly fade from view? The astronomy word of the week is "nova". Bio: Dr. Christopher Crockett is an astronomer at the United States Naval Observatory in Flagstaff, Arizona. His research involves searching for planets around very young stars (“only” a few million years old). It is hoped that the results from this research will help constrain models of planet formation and lead to a better understanding of where, when, and how often planets form. Chris is also passionate about astronomy outreach and education and will talk for hours about the Universe if you let him. Sponsors: Sponsorship for this episode of "365 days of Astronomy" is donated anonymously and dedicated to the men and women of NASA who strive to turn science fiction into science reality. Additional sponsorship for this episode has been provided by iTelescope.net - Expanding your horizons in astronomy today. The premier on-demand telescope network, at dark sky sites in Spain, New Mexico and Siding Spring, Australia. Transcript: In 1572, Danish astronomer Tycho Brahe, along with observers around the world, noticed a new star in the constellation Casseiopeia. Rivaling Venus as the brightest object in the night sky after the Moon, the unexpected guest remained visible for nearly two years before fading from view. The appearance of a new star was nothing short of revolutionary; astronomers long agreed that the celestial sphere was unchanging. A transient star challenged this assumption and suggested that the heavens were perhaps more dynamic than originally thought. The celestial intruder came to be known as a "nova" - after Tycho Brahe's extensive manuscript on the phenomenon - where he referred to the object simply by the latin term for a new star: "stella nova". While no one could have known it at the time, the new star was actually not new at all but rather a very old star experiencing a cataclysmic event. Most of the stars in the sky are not singular, like our Sun, but rather members of binary star systems - two stars locked in orbit around one another. Of this pair, one star is often more massive than its companion and therefore burns through its nuclear fuel at a faster rate. The heavier star reaches the end of its life before its sibling. When it does, the star inflates to become a red giant and sheds its outer layers into space leaving behind the hot, dense stellar core. The naked core, known as a "white dwarf", continues to orbit its stellar neighbor while taking the next few billion years to passively cool from a white-hot 100,000 degrees. In the case of close binary pairs, the white dwarf can actually siphon matter off of its companion. The intermingled gravitational fields of the two stars builds a bridge of predominately hydrogen gas spanning the distance between them. Gas from the still active star flows through this gravitational funnel and spills on to the surface of the white dwarf. The mass of the white dwarf controls the rate of mass accretion; if the rate is high enough, then something quite spectacular can happen. White dwarfs are an example of a rather exotic type of matter that physicists call "degenerate". Most gasses expand when you heat them up: the increasing temperature causes the molecules to zip around faster which in turn increases the gas pressure. At extreme densities - like those seen in the cores of stars - the gas behaves rather peculiarly. The pressure is no longer a slave to temperature: turn up the heat and the gas does not expand. This counterintuitive behavior is crucial to what happens next on the white dwarf's surface. As hydrogen from the donor star comes crashing down, the crushing force of gravity compresses it into a degenerate state and the intense radiation heats the gas to many millions of degrees. But having now obtained the properties of a degenerate gas, the newly acquired hydrogen shell doesn't expand in response to the rapid heating, but holds its pressure steady. And now things get interesting. At temperatures exceeding 16 million degrees Celsius, conditions on the surface mimic those deep in the cores of stars and a thermonuclear explosion is the result. Hydrogen is rapidly fused into helium and the resulting release of energy blows the outer hydrogen shell off the surface of the white dwarf at speeds exceeding ten million kilometers per hour. In mere days, the white dwarf can increase its brightness by 100,000 times. It can then take months - or in some cases years - for the star to slowly fade from view. Our Milky Way Galaxy experiences several dozen novae each year, only about ten of which are visible from Earth. A few are even visible to the naked eye. The most recent nova to be seen without the aid of binoculars or telescopes did so in the constellation Scorpius, reaching its peak brightness on February 17, 2007. Even more rare are what astronomers call "recurrent nova". Once the white dwarf has blown the hydrogen shell into space, the gas can slowly start building up again. These are novae that flare up repeatedly, sometimes once a year, sometimes once every couple of decades. In our whole galaxy, only ten novae are known to be recurrent. In the centuries since the new star of 1572, astronomers have come to realize that the event which gave novae their name was not what we know now as a nova. Up until early in the 20th century, a nova referred to any rapid brightening of a star. But there are many reasons stars suddenly flare into view. What Tycho saw was actually something far more powerful - a type of, aptly named, supernova. The supernova of 1572 was not the result of a flash of hydrogen burning on a white dwarf shell, but rather was caused by the complete detonation of a white dwarf. By stealing gas from a nearby companion slowly enough, the progenitor of the supernova delayed a nova flash while gradually increasing its temperature and pressure and eventually igniting hydrogen fusion throughout the interior of the once dead stellar core. With out the counterbalancing force of the rest of the star to throttle these reactions, the now violently active core obliterated itself in one of the most powerful explosions the Universe can produce. The event of 1572 ushered in a new era of astronomy, one in which the constancy of the celestial sphere could no longer be assumed. Novae - and their more powerful supernovae cousins - are constant reminders that we, in fact, live in a highly dynamic and energetic Universe. End of podcast: 365 Days of Astronomy ===================== The 365 Days of Astronomy Podcast is produced by the Astrosphere New Media Association. Audio post-production by Preston Gibson. Bandwidth donated by libsyn.com and wizzard media. Web design by Clockwork Active Media Systems. You may reproduce and distribute this audio for non-commercial purposes. Please consider supporting the podcast with a few dollars (or Euros!). Visit us on the web at 365DaysOfAstronomy.org or email us at info@365DaysOfAstronomy.org. Until tomorrow...goodbye.]]> http://365daysofastronomy.org/2012/05/09/may-9th-astronomy-word-of-the-week-nova/feed/ 0 podcast iya 365 Date: May 9, 2012 - Title: Astronomy Word of the Week: Nova - Podcaster: Dr. Christopher Crockett - Organization: United States Naval Observatory - Links: http://christophercrockett.com http://astrowow.wordpress.com/ - Date: May 9, 2012 Title: Astronomy Word of the Week: Nova Podcaster: Dr. Christopher Crockett Organization: United States Naval Observatory Links: http://christophercrockett.com http://astrowow.wordpress.com/ Description: Why do once invisible stars suddenly flare up and then slowly fade from view? The astronomy word of the week is "nova". Bio: Dr. Christopher Crockett is an astronomer at the United States Naval Observatory in Flagstaff, Arizona. His research involves searching for planets around very young stars (“only” a few million years old). It is hoped that the results from this research will help constrain models of planet formation and lead to a better understanding of where, when, and how often planets form. Chris is also passionate about astronomy outreach and education and will talk for hours about the Universe if you let him. Sponsors: Sponsorship for this episode of "365 days of Astronomy" is donated anonymously and dedicated to the men and women of NASA who strive to turn science fiction into science reality. Additional sponsorship for this episode has been provided by iTelescope.net - Expanding your horizons in astronomy today. The premier on-demand telescope network, at dark sky sites in Spain, New Mexico and Siding Spring, Australia. Transcript: In 1572, Danish astronomer Tycho Brahe, along with observers around the world, noticed a new star in the constellation Casseiopeia. Rivaling Venus as the brightest object in the night sky after the Moon, the unexpected guest remained visible for nearly two years before fading from view. The appearance of a new star was nothing short of revolutionary; astronomers long agreed that the celestial sphere was unchanging. A transient star challenged this assumption and suggested that the heavens were perhaps more dynamic than originally thought. The celestial intruder came to be known as a "nova" - after Tycho Brahe's extensive manuscript on the phenomenon - where he referred to the object simply by the latin term for a new star: "stella nova". While no one could have known it at the time, the new star was actually not new at all but rather a very old star experiencing a cataclysmic event. Most of the stars in the sky are not singular, like our Sun, but rather members of binary star systems - two stars locked in orbit around one another. Of this pair, one star is often more massive than its companion and therefore burns through its nuclear fuel at a faster rate. The heavier star reaches the end of its life before its sibling. When it does, the star inflates to become a red giant and sheds its outer layers into space leaving behind the hot, dense stellar core. The naked core, known as a "white dwarf", continues to orbit its stellar neighbor while taking the next few billion years to passively cool from a white-hot 100,000 degrees. In the case of close binary pairs, the white dwarf can actually siphon matter off of its companion. The intermingled gravitational fields of the two stars builds a bridge of predominately hydrogen gas spanning the distance between them. Gas from the still active star flows through this gravitational funnel and spills on to the surface of the white dwarf. The mass of the white dwarf controls the rate of mass accretion; if the rate is high enough, then something quite spectacular can happen. White dwarfs are an example of a rather exotic type of matter that physicists call "degenerate". Most gasses expand when you heat them up: the increasing temperature causes the molecules to zip around faster which in turn increases the gas pressure. At extreme densities - like those seen in the cores of stars - the gas behaves rather peculiarly. The pressure is no longer a slave to temperature: turn up the heat and the gas does not expand. This counterintuitive behavior is crucial to what happens next on the white dwarf's surface. As hydrogen from the donor star comes crashing down, 365 Days of Astronomy no May 8th: What is Black http://365daysofastronomy.org/2012/05/08/may-8th-what-is-black/ http://365daysofastronomy.org/2012/05/08/may-8th-what-is-black/#comments Tue, 08 May 2012 11:00:41 +0000 kortney.hogan http://365daysofastronomy.org/?p=7646 Date: May 8, 2012 Title: What is Black Podcaster: Rob Sparks & Dr. Steven Pompea Organization: NOAO Links: www.noao.edu Description: Most people think of black as a color, but black is really the absence of light. Truly black surfaces reflect almost none of the light that falls on them. In this podcast, Dr. Stephen Pompea discusses black surface, how they are produced and why they are important in astronomy and other sciences. Bio: Rob Sparks is a science education specialist in the EPO group at NOAO and works on the Galileoscope project (www.galileoscope.org), providing design, dissemination and professional development. He also pens a great blog at halfastro.wordpress.com. Dr. Stephen Pompea did his undergraduate work in physics, space physics, and astronomy at Rice University, his Master’s work in physics teaching at Colorado State University, and his Ph.D. in astronomy at the University of Arizona. He is currently the manager of the Education and Public Outreach Group at the National Optical Astronomy Observatory. Sponsor: This episode of the 365 Days of Astronomy podcast is sponsored by the National Optical Astronomy Observatory. NOAO is a US national research and development center for ground-based nighttime astronomy. We provide astronomers access to world-class observing facilities on a peer-reviewed basis. Our mission is to engage in programs to develop the next generation of telescopes, instruments, and software tools necessary to enable exploration and investigation through the observable Universe. For information on observing proposals or our public programs, please visit www.noao.edu for more information. "This episode has also been sponsored by the Lake County Astronomical Society: Celebrating 30 years of stellar service to members and the public." Transcript: *** Transcript coming soon. *** End of podcast: 365 Days of Astronomy ===================== The 365 Days of Astronomy Podcast is produced by the Astrosphere New Media Association. Audio post-production by Preston Gibson. Bandwidth donated by libsyn.com and wizzard media. Web design by Clockwork Active Media Systems. You may reproduce and distribute this audio for non-commercial purposes. Please consider supporting the podcast with a few dollars (or Euros!). Visit us on the web at 365DaysOfAstronomy.org or email us at info@365DaysOfAstronomy.org. Until tomorrow...goodbye.]]> http://365daysofastronomy.org/2012/05/08/may-8th-what-is-black/feed/ 0 podcast iya 365 Date: May 8, 2012 - Title: What is Black - Podcaster: Rob Sparks & Dr. Steven Pompea - Organization: NOAO - Links: www.noao.edu - Description: Most people think of black as a color, but black is really the absence of light. Date: May 8, 2012 Title: What is Black Podcaster: Rob Sparks & Dr. Steven Pompea Organization: NOAO Links: www.noao.edu Description: Most people think of black as a color, but black is really the absence of light. Truly black surfaces reflect almost none of the light that falls on them. In this podcast, Dr. Stephen Pompea discusses black surface, how they are produced and why they are important in astronomy and other sciences. Bio: Rob Sparks is a science education specialist in the EPO group at NOAO and works on the Galileoscope project (www.galileoscope.org), providing design, dissemination and professional development. He also pens a great blog at halfastro.wordpress.com. Dr. Stephen Pompea did his undergraduate work in physics, space physics, and astronomy at Rice University, his Master’s work in physics teaching at Colorado State University, and his Ph.D. in astronomy at the University of Arizona. He is currently the manager of the Education and Public Outreach Group at the National Optical Astronomy Observatory. Sponsor: This episode of the 365 Days of Astronomy podcast is sponsored by the National Optical Astronomy Observatory. NOAO is a US national research and development center for ground-based nighttime astronomy. We provide astronomers access to world-class observing facilities on a peer-reviewed basis. Our mission is to engage in programs to develop the next generation of telescopes, instruments, and software tools necessary to enable exploration and investigation through the observable Universe. For information on observing proposals or our public programs, please visit www.noao.edu for more information. "This episode has also been sponsored by the Lake County Astronomical Society: Celebrating 30 years of stellar service to members and the public." Transcript: *** Transcript coming soon. *** End of podcast: 365 Days of Astronomy ===================== The 365 Days of Astronomy Podcast is produced by the Astrosphere New Media Association. Audio post-production by Preston Gibson. Bandwidth donated by libsyn.com and wizzard media. Web design by Clockwork Active Media Systems. You may reproduce and distribute this audio for non-commercial purposes. Please consider supporting the podcast with a few dollars (or Euros!). Visit us on the web at 365DaysOfAstronomy.org or email us at info@365DaysOfAstronomy.org. Until tomorrow...goodbye. 365 Days of Astronomy no May 7th: The Late Heavy Bombardment — an Extended Version? http://365daysofastronomy.org/2012/05/09/may-9th-astronomy-word-of-the-week-nova/ http://365daysofastronomy.org/2012/05/09/may-9th-astronomy-word-of-the-week-nova/#comments Wed, 09 May 2012 11:00:09 +0000 kortney.hogan http://365daysofastronomy.org/?p=7650 Date: May 9, 2012 Title: Astronomy Word of the Week: Nova Podcaster: Dr. Christopher Crockett Organization: United States Naval Observatory Links: http://christophercrockett.com http://astrowow.wordpress.com/ Description: Why do once invisible stars suddenly flare up and then slowly fade from view? The astronomy word of the week is "nova". Bio: Dr. Christopher Crockett is an astronomer at the United States Naval Observatory in Flagstaff, Arizona. His research involves searching for planets around very young stars (“only” a few million years old). It is hoped that the results from this research will help constrain models of planet formation and lead to a better understanding of where, when, and how often planets form. Chris is also passionate about astronomy outreach and education and will talk for hours about the Universe if you let him. Sponsors: Sponsorship for this episode of "365 days of Astronomy" is donated anonymously and dedicated to the men and women of NASA who strive to turn science fiction into science reality. Additional sponsorship for this episode has been provided by iTelescope.net - Expanding your horizons in astronomy today. The premier on-demand telescope network, at dark sky sites in Spain, New Mexico and Siding Spring, Australia. Transcript: In 1572, Danish astronomer Tycho Brahe, along with observers around the world, noticed a new star in the constellation Casseiopeia. Rivaling Venus as the brightest object in the night sky after the Moon, the unexpected guest remained visible for nearly two years before fading from view. The appearance of a new star was nothing short of revolutionary; astronomers long agreed that the celestial sphere was unchanging. A transient star challenged this assumption and suggested that the heavens were perhaps more dynamic than originally thought. The celestial intruder came to be known as a "nova" - after Tycho Brahe's extensive manuscript on the phenomenon - where he referred to the object simply by the latin term for a new star: "stella nova". While no one could have known it at the time, the new star was actually not new at all but rather a very old star experiencing a cataclysmic event. Most of the stars in the sky are not singular, like our Sun, but rather members of binary star systems - two stars locked in orbit around one another. Of this pair, one star is often more massive than its companion and therefore burns through its nuclear fuel at a faster rate. The heavier star reaches the end of its life before its sibling. When it does, the star inflates to become a red giant and sheds its outer layers into space leaving behind the hot, dense stellar core. The naked core, known as a "white dwarf", continues to orbit its stellar neighbor while taking the next few billion years to passively cool from a white-hot 100,000 degrees. In the case of close binary pairs, the white dwarf can actually siphon matter off of its companion. The intermingled gravitational fields of the two stars builds a bridge of predominately hydrogen gas spanning the distance between them. Gas from the still active star flows through this gravitational funnel and spills on to the surface of the white dwarf. The mass of the white dwarf controls the rate of mass accretion; if the rate is high enough, then something quite spectacular can happen. White dwarfs are an example of a rather exotic type of matter that physicists call "degenerate". Most gasses expand when you heat them up: the increasing temperature causes the molecules to zip around faster which in turn increases the gas pressure. At extreme densities - like those seen in the cores of stars - the gas behaves rather peculiarly. The pressure is no longer a slave to temperature: turn up the heat and the gas does not expand. This counterintuitive behavior is crucial to what happens next on the white dwarf's surface. As hydrogen from the donor star comes crashing down, the crushing force of gravity compresses it into a degenerate state and the intense radiation heats the gas to many millions of degrees. But having now obtained the properties of a degenerate gas, the newly acquired hydrogen shell doesn't expand in response to the rapid heating, but holds its pressure steady. And now things get interesting. At temperatures exceeding 16 million degrees Celsius, conditions on the surface mimic those deep in the cores of stars and a thermonuclear explosion is the result. Hydrogen is rapidly fused into helium and the resulting release of energy blows the outer hydrogen shell off the surface of the white dwarf at speeds exceeding ten million kilometers per hour. In mere days, the white dwarf can increase its brightness by 100,000 times. It can then take months - or in some cases years - for the star to slowly fade from view. Our Milky Way Galaxy experiences several dozen novae each year, only about ten of which are visible from Earth. A few are even visible to the naked eye. The most recent nova to be seen without the aid of binoculars or telescopes did so in the constellation Scorpius, reaching its peak brightness on February 17, 2007. Even more rare are what astronomers call "recurrent nova". Once the white dwarf has blown the hydrogen shell into space, the gas can slowly start building up again. These are novae that flare up repeatedly, sometimes once a year, sometimes once every couple of decades. In our whole galaxy, only ten novae are known to be recurrent. In the centuries since the new star of 1572, astronomers have come to realize that the event which gave novae their name was not what we know now as a nova. Up until early in the 20th century, a nova referred to any rapid brightening of a star. But there are many reasons stars suddenly flare into view. What Tycho saw was actually something far more powerful - a type of, aptly named, supernova. The supernova of 1572 was not the result of a flash of hydrogen burning on a white dwarf shell, but rather was caused by the complete detonation of a white dwarf. By stealing gas from a nearby companion slowly enough, the progenitor of the supernova delayed a nova flash while gradually increasing its temperature and pressure and eventually igniting hydrogen fusion throughout the interior of the once dead stellar core. With out the counterbalancing force of the rest of the star to throttle these reactions, the now violently active core obliterated itself in one of the most powerful explosions the Universe can produce. The event of 1572 ushered in a new era of astronomy, one in which the constancy of the celestial sphere could no longer be assumed. Novae - and their more powerful supernovae cousins - are constant reminders that we, in fact, live in a highly dynamic and energetic Universe. End of podcast: 365 Days of Astronomy ===================== The 365 Days of Astronomy Podcast is produced by the Astrosphere New Media Association. Audio post-production by Preston Gibson. Bandwidth donated by libsyn.com and wizzard media. Web design by Clockwork Active Media Systems. You may reproduce and distribute this audio for non-commercial purposes. Please consider supporting the podcast with a few dollars (or Euros!). Visit us on the web at 365DaysOfAstronomy.org or email us at info@365DaysOfAstronomy.org. Until tomorrow...goodbye.]]> http://365daysofastronomy.org/2012/05/09/may-9th-astronomy-word-of-the-week-nova/feed/ 0 podcast iya 365 Date: May 9, 2012 - Title: Astronomy Word of the Week: Nova - Podcaster: Dr. Christopher Crockett - Organization: United States Naval Observatory - Links: http://christophercrockett.com http://astrowow.wordpress.com/ - Date: May 9, 2012 Title: Astronomy Word of the Week: Nova Podcaster: Dr. Christopher Crockett Organization: United States Naval Observatory Links: http://christophercrockett.com http://astrowow.wordpress.com/ Description: Why do once invisible stars suddenly flare up and then slowly fade from view? The astronomy word of the week is "nova". Bio: Dr. Christopher Crockett is an astronomer at the United States Naval Observatory in Flagstaff, Arizona. His research involves searching for planets around very young stars (“only” a few million years old). It is hoped that the results from this research will help constrain models of planet formation and lead to a better understanding of where, when, and how often planets form. Chris is also passionate about astronomy outreach and education and will talk for hours about the Universe if you let him. Sponsors: Sponsorship for this episode of "365 days of Astronomy" is donated anonymously and dedicated to the men and women of NASA who strive to turn science fiction into science reality. Additional sponsorship for this episode has been provided by iTelescope.net - Expanding your horizons in astronomy today. The premier on-demand telescope network, at dark sky sites in Spain, New Mexico and Siding Spring, Australia. Transcript: In 1572, Danish astronomer Tycho Brahe, along with observers around the world, noticed a new star in the constellation Casseiopeia. Rivaling Venus as the brightest object in the night sky after the Moon, the unexpected guest remained visible for nearly two years before fading from view. The appearance of a new star was nothing short of revolutionary; astronomers long agreed that the celestial sphere was unchanging. A transient star challenged this assumption and suggested that the heavens were perhaps more dynamic than originally thought. The celestial intruder came to be known as a "nova" - after Tycho Brahe's extensive manuscript on the phenomenon - where he referred to the object simply by the latin term for a new star: "stella nova". While no one could have known it at the time, the new star was actually not new at all but rather a very old star experiencing a cataclysmic event. Most of the stars in the sky are not singular, like our Sun, but rather members of binary star systems - two stars locked in orbit around one another. Of this pair, one star is often more massive than its companion and therefore burns through its nuclear fuel at a faster rate. The heavier star reaches the end of its life before its sibling. When it does, the star inflates to become a red giant and sheds its outer layers into space leaving behind the hot, dense stellar core. The naked core, known as a "white dwarf", continues to orbit its stellar neighbor while taking the next few billion years to passively cool from a white-hot 100,000 degrees. In the case of close binary pairs, the white dwarf can actually siphon matter off of its companion. The intermingled gravitational fields of the two stars builds a bridge of predominately hydrogen gas spanning the distance between them. Gas from the still active star flows through this gravitational funnel and spills on to the surface of the white dwarf. The mass of the white dwarf controls the rate of mass accretion; if the rate is high enough, then something quite spectacular can happen. White dwarfs are an example of a rather exotic type of matter that physicists call "degenerate". Most gasses expand when you heat them up: the increasing temperature causes the molecules to zip around faster which in turn increases the gas pressure. At extreme densities - like those seen in the cores of stars - the gas behaves rather peculiarly. The pressure is no longer a slave to temperature: turn up the heat and the gas does not expand. This counterintuitive behavior is crucial to what happens next on the white dwarf's surface. As hydrogen from the donor star comes crashing down, 365 Days of Astronomy no 365 Days of Astronomy http://365daysofastronomy.org An astronomy podcast every day, all year Wed, 16 May 2012 11:00:41 +0000 en hourly 1 http://wordpress.org/?v=3.1 An astronomy podcast every day, all year 365 Days of Astronomy no An astronomy podcast every day, all year 365 Days of Astronomy http://365daysofastronomy.org/wp-content/plugins/powerpress/rss_default.jpg http://365daysofastronomy.org May 16th: GPS http://365daysofastronomy.org/2012/05/16/may-16th-gps/ http://365daysofastronomy.org/2012/05/16/may-16th-gps/#comments Wed, 16 May 2012 11:00:41 +0000 kortney.hogan http://365daysofastronomy.org/?p=7689 Date: May 16, 2012 Title: GPS Podcaster: Steve Nerlich Organization: Cheap Astronomy Links: www.cheapastro.com Description: Cheap Astronomy once again demonstrates that pretty much everything in life has a connection to astronomy. Bio: Cheap Astronomy offers an educational website because in space no-one can hear you podcast. Today's Sponsor: "This episode of 365 days of Astronomy" is sponsored by the Lake County Astronomical Society: Celebrating 30 years of stellar service to members and the public." Additional sponsorship for this episode has also been provided by iTelescope.net - Expanding your horizons in astronomy today. The premier on-demand telescope network, at dark sky sites in Spain, New Mexico and Siding Spring, Australia. Transcript: Hi this is Steve Nerlich from Cheap Astronomy www.cheapastro.com and this is GPS OK – If you don’t have one, you know someone who does, so let’s skip the introductions and get straight down to the astronomy. A standard GPS configuration is a constellation of 24 GPS satellites. The satellites are all at an altitude of 20,200 km with an orbital period of 11 hours and 58 minutes – which means they do exactly 2 orbits for each time the Earth spins once on its axis. Four satellites each follow six orbital planes separated by 60 degrees which surround the Earth in an (airquotes) ‘birdcage’ of criss-crossing orbits. There a link to the relevant Wikipedia article from the Cheap Astronomy podcast page which has a nice animation of a GPS satellite constellation. At last count, there were actually 31 actively transmitting GPS satellites – with these extra number increasing location accuracy and redundancy. There’s been some recent media regarding a growing risk of dropping below the minimum 24 active satellites required to make GPS work effectively, but it remains to be seen if this risk will be realised in the face of the increasing economic importance of maintaining a working GPS system. A GPS satellite broadcasts a signal indicating where it is and the time the signal was broadcast – your receiver then determines, from the time it receives that signal, the distance travelled by the signal, knowing that, being a radio transmission, the signal travels at the speed of light. By making just four calculations from four satellites in the sky, your GPS receiver can then establish its position with respect to latitude, longitude and altitude. It’s all about the conjunction of spheres. Imagine one satellite broadcasting a radio signal. If you pick up that signal and determine it’s a 100 km away, all you really know is that you are somewhere on a surface of a sphere with a 100 km radius that has the satellite at its centre. If there’s two such satellites then you’ll know you are somewhere on the circumference of a circle representing the plane where the two spheres of radio broadcast overlap. Introduce a third satellite and you can narrow down your location to just two points in space which are the points where two differently orientated circle circumferences intersect. Potentially this may be enough to roughly determine your position since you can anticipate you will be on the one of those two points corresponding to the surface of the Earth. But for strictest accuracy – including accuracy in determining your altitude above sea level, the signal from a fourth satellite is required. And that is the idea of the constellation of GPS satellites. Keeping 24 satellites moving in the same orbit, tracing a birdcage of divergent paths around the globe ensures there will always be four satellites in the sky wherever you happen to be on Earth. Now when I say GPS satellites just have to broadcast where they are – actually knowing where they are is a whole separate operation, While the orbital period is predictable, knowing at what point they are on that orbit requires some very accurate time keeping – for which reason each satellite has an atomic clock. Nonetheless, even this isn’t enough, as the orbital paths of the satellites are subject to slight shifting due to the gravitational influence of the Sun and the Moon. To keep track of these changes the satellites are monitored from a fixed, known location on the Earth’s surface – a function currently managed by the 50th Space Wing of the US Airforce Space Command – seriously. Now, given that your GPS receiver is working out its distance from each of four satellites based solely on the time lag of a signal moving at the speed of light from a satellite just over 20,000 kilometres away – there is considerable potential for a margin of error that could see you driving over the embankment into a river when that sexy voice says ‘turn left now’. There are a range of methods to deal with various sources of error. Firstly your GPS receiver carries an electronic almanac of which satellite should be where since confusion can arise when the satellite radio signals get reflected off surroundings, such as tall buildings. This electronic almanac is constructed from calibration data received from the GPS satellites, although these data are generally relayed from a ground-based source – such as Airforce Space Command. The almanac helps your receiver distinguish between garbage signals and genuine GPS signals. The receiver also receives time checks from the satellites since, most GPS receivers determine time from a cheap (not that there’s anything wrong with that) quartz clock rather than the ultra-accurate atomic clocks of the satellites. Clock error is probably the biggest potential source of GPS error, which is why, even though you could almost get away with determining your position from just 3 satellites, it is the fourth reading (which we might call quadrangulation) that ensures the poorer accuracy of the GPS receiver’s clock is effectively accounted for. Interestingly, there’s also relativistic effects to account for, since the satellites move in a weaker gravity field (meaning by general relativity their clocks run faster), and they also move at speed relative to the surface of the Earth (meaning by special relativity their clocks run slower). It turns out that the nett effect is that the satellites’ clocks run about 38 microseconds per day faster than they would at the Earth’s surface. To account for this, the clocks are actually set to run at a slightly lower rate, to keep pace with clocks running on the Earth’s surface. In the world of atomic clocks, various time keeping callibrations are also required to account for changes in the rotation of the Earth – which is influenced by the tidal drag of the Moon , the inertia of the Earth’s molten interior and even the melting of glaciers. Overall, the Earth’s rotation is slowing, leading to a lengthening of a solar day. Consequently a leap second must be introduced to atomic timepieces which measure Universal Coordinated Time (known as UTC – because of the French). In fact, a leap second is required to be added to UTC every 18 months or so because each year (on average) the length of a solar day increases by about 0.002 seconds. The atomic clocks of GPS satellites were aligned to UTC in 1980 – but as of 2009, these atomic clocks in orbit now vary by 19 seconds and to keep it simple we just say they are running at GPS time. Various under-the-hood adjustments are made along the way so that your GPS receiver can tell you the local time wherever you happen to be – as well as telling you where you are of course to within… well, within 10 metres is the general benchmark, although this takes a few minutes to establish after the unit is turned on and the accuracy will degrade with tall trees or buildings around. So, you know, it’s a guide – not an absolute – it’s still a good idea to keep one eye on the road. Thanks for listening. This is Steve Nerlich from Cheap Astronomy, www.cheapastro.com. Cheap Astronomy offers an educational website where you can’t put a price on space. No ads, no profit, just good science. Bye. End of podcast: 365 Days of Astronomy ===================== The 365 Days of Astronomy Podcast is produced by the New Media Working Group of the International Year of Astronomy 2009. Audio post-production by Preston Gibson. Bandwidth donated by libsyn.com and wizzard media. Web design by Clockwork Active Media Systems. You may reproduce and distribute this audio for non-commercial purposes. Please consider supporting the podcast with a few dollars (or Euros!). Visit us on the web at 365DaysOfAstronomy.org or email us at info@365DaysOfAstronomy.org. Until tomorrow...goodbye.]]> http://365daysofastronomy.org/2012/05/16/may-16th-gps/feed/ 0 podcast iya 365 Date: May 16, 2012 - Title: GPS Podcaster: Steve Nerlich - Organization: Cheap Astronomy - Links: www.cheapastro.com - Description: Cheap Astronomy once again demonstrates that pretty much everything in life has a connection to astronomy. - Date: May 16, 2012 Title: GPS Podcaster: Steve Nerlich Organization: Cheap Astronomy Links: www.cheapastro.com Description: Cheap Astronomy once again demonstrates that pretty much everything in life has a connection to astronomy. B... 365 Days of Astronomy no May 15th: Astronomy Word of the Week: Obliquity http://365daysofastronomy.org/2012/05/15/may-15th-astronomy-word-of-the-week-obliquity/ http://365daysofastronomy.org/2012/05/15/may-15th-astronomy-word-of-the-week-obliquity/#comments Tue, 15 May 2012 11:00:14 +0000 kortney.hogan http://365daysofastronomy.org/?p=7687 Date: May 15, 2012 Title: Astronomy Word of the Week: Obliquity Podcaster: Dr. Christopher Crockett Organization: United States Naval Observatory Links: http://christophercrockett.com http://astrowow.wordpress.com/ Description: The tilt of our planet is about much more than the seasons. The astronomy word of the week is "obliquity". Bio: Dr. Christopher Crockett is an astronomer at the United States Naval Observatory in Flagstaff, Arizona. His research involves searching for planets around very young stars (“only” a few million years old). It is hoped that the results from this research will help constrain models of planet formation and lead to a better understanding of where, when, and how often planets form. Chris is also passionate about astronomy outreach and education and will talk for hours about the Universe if you let him. Today's Sponsor: "This episode of 365 days of Astronomy" is sponsored by iTelescope.net - Expanding your horizons in astronomy today. The premier on-demand telescope network, at dark sky sites in Spain, New Mexico and Siding Spring, Australia. This episode has also been sponsored by Lake County Astronomical Society: Celebrating 30 years of stellar service to members and the public. Transcript: The planet you're standing on is not very steady. She bobs and wobbles, ducks and weaves, as she makes her annual trek around the Sun. Our home constantly struggles with forces both external and internal; the Sun, the Moon, and the planets tug her back and forth while shifting masses within force her to constantly find new balance. The tilt of our planet's axis - what astronomers call its obliquity - is one measure of this interplanetary tug-of-war. Obliquity measures how far over a planet or moon is tipped relative to its orbit; in the Earth's case, it's about 23 degrees. We feel the obliquity in the changing seasons. In June, the north pole is tipped towards the Sun. The northern hemisphere experiences longer days and more direct sunlight giving us warm summer days. In December, the north pole is tipped away from the Sun and everyone above the equator experiences the bitter chill of winter as the days get shorter and the sunlight reaches us more obliquely. The other planets in our solar system exhibit a wide range of obliquities. Mars, Saturn, and Neptune are all tipped by roughly the same amount as Earth. Mercury and Jupiter have hardly any obliquity at all - which means no seasons for them. Venus' obliquity is 177 degrees; it is almost completely upside down. Put another way, it rotates in the opposite direction from Earth. Were there ever to be a break in Venus' stifling cloud layer, native Venusians would see the Sun rise in the west and set in the east! Uranus is another strange character; his obliquity is 97 degrees. Uranus is lying on his side! This leads to some very strange days and seasons. Each pole of Uranus alternates between being in constant sunlight for 42 years, then perpetual darkness for another 42 years. Only a very thin strip along the equator experiences anything like day/night cycles that we experience - and even then the Sun is frequently sitting very low on the horizon. Astronomers aren't entirely certain how Venus and Uranus came to have such extreme obliquities. A leading hypothesis is that both experienced massive collisions at some point in their distant past, essentially knocking them over. A glancing blow from a minor planet isn't the only thing that can change an obliquity. The tilt of our planet's axis is drifting - ever so slightly - all the time. The poles actually trace out a rather complex dance over time scales ranging from minutes to thousands of centuries. Like a spinning top, our planet also wobbles - though it does so very slowly. Over a period of 26,000 years, the poles trace out a giant circle in the sky. Right now, the north pole points pretty close to the star Polaris. But over time that will change, and in some epochs it will be pointing at nothing at all. This wobble - or precession - doesn't change the amount of obliquity; it simply changes where in space the poles are pointing. The Moon, however, does tug on our planet's axis. In addition to rotation and precession, the Earth experiences something called nutation. This is a slight rocking of the Earth's axis caused by the changing positions of the Moon, the Sun, and all the other bodies in the solar system. With many players involved, the motion from nutation is fairly complex. The main component nods the planet by a couple hundred meters over a nearly 19 year cycle that is tied to how the Moon's orbit drifts around the Earth. Our planet also has to contend with forces much closer to home. Internal motions of magma, deep sea currents, changing ocean salinity, winds, melting ice sheets, and even earthquakes all conspire to constantly change the distribution of mass within the Earth. The planet responds by continuously shifting its spin axis - an effect known as polar motion. This is a bit different than nutation; it actually changes where on Earth the north and south poles are located. Hard as it may be to fathom, these are not fixed locations on the globe. The drift is very small - centimeters per year - but it does add a complex twist to understanding our planets motion in space. The presence of a large moon is believed to help stabilize our obliquity. The tilt does change by a few degrees over many millions of years, but manages to hold steady at around 20-25 degrees. Mars, conversely, appears to be going through a chaotic evolution in its obliquity. Computer simulations of its stability suggest that, over the past few million years, the Red Planet's tilt has oscillated wildly between zero and sixty degrees which may lead to drastic swings in the environment. Many astrobiologists - scientists who study the evolution and origin of life in a cosmic context - argue that our moon may be an essential ingredient for providing a stable environment within which life could thrive. Does this mean that the existence of complex life and advanced civilizations is dependent on the presence of a large satellite? That's hard to say. It is certainly plausible that our closest neighbor in space has been an indispensable partner in the evolution of our species. I'm continually amazed at how a simple concept - like the tilt of a planet - can actually lead down a labyrinthian path of subtleties. Studying Earth's obliquity, and the obliquity of all the other planets and moons, reveals much about the dynamics of our planet, the interplay of our home and neighboring worlds, and even the often times cataclysmic evolution of the solar system. While the subtleties are far removed from our day-to-day lives, our Earth's position in space actually is inseparable from the human experience. The June solstice is just over a month away. Whether you're bundling up for winter, or heading to the beach for summer, remember: the Earth's obliquity is the reason for the seasons! End of podcast: 365 Days of Astronomy ===================== The 365 Days of Astronomy Podcast is produced by the New Media Working Group of the International Year of Astronomy 2009. Audio post-production by Preston Gibson. Bandwidth donated by libsyn.com and wizzard media. Web design by Clockwork Active Media Systems. You may reproduce and distribute this audio for non-commercial purposes. Please consider supporting the podcast with a few dollars (or Euros!). Visit us on the web at 365DaysOfAstronomy.org or email us at info@365DaysOfAstronomy.org. Until tomorrow...goodbye.]]> http://365daysofastronomy.org/2012/05/15/may-15th-astronomy-word-of-the-week-obliquity/feed/ 0 podcast iya 365 Date: May 15, 2012 - Title: Astronomy Word of the Week: Obliquity Podcaster: Dr. Christopher Crockett - Organization: United States Naval Observatory - Links: http://christophercrockett.com http://astrowow.wordpress.com/ - Date: May 15, 2012 Title: Astronomy Word of the Week: Obliquity Podcaster: Dr. Christopher Crockett Organization: United States Naval Observatory Links: http://christophercrockett.com http://astrowow.wordpress.com/ Description: The tilt of our planet is about much more than the seasons. The astronomy word of the week is "obliquity". Bio: Dr. Christopher Crockett is an astronomer at the United States Naval Observatory in Flagstaff, Arizona. His research involves searching for planets around very young stars (“only” a few million years old). It is hoped that the results from this research will help constrain models of planet formation and lead to a better understanding of where, when, and how often planets form. Chris is also passionate about astronomy outreach and education and will talk for hours about the Universe if you let him. Today's Sponsor: "This episode of 365 days of Astronomy" is sponsored by iTelescope.net - Expanding your horizons in astronomy today. The premier on-demand telescope network, at dark sky sites in Spain, New Mexico and Siding Spring, Australia. This episode has also been sponsored by Lake County Astronomical Society: Celebrating 30 years of stellar service to members and the public. Transcript: The planet you're standing on is not very steady. She bobs and wobbles, ducks and weaves, as she makes her annual trek around the Sun. Our home constantly struggles with forces both external and internal; the Sun, the Moon, and the planets tug her back and forth while shifting masses within force her to constantly find new balance. The tilt of our planet's axis - what astronomers call its obliquity - is one measure of this interplanetary tug-of-war. Obliquity measures how far over a planet or moon is tipped relative to its orbit; in the Earth's case, it's about 23 degrees. We feel the obliquity in the changing seasons. In June, the north pole is tipped towards the Sun. The northern hemisphere experiences longer days and more direct sunlight giving us warm summer days. In December, the north pole is tipped away from the Sun and everyone above the equator experiences the bitter chill of winter as the days get shorter and the sunlight reaches us more obliquely. The other planets in our solar system exhibit a wide range of obliquities. Mars, Saturn, and Neptune are all tipped by roughly the same amount as Earth. Mercury and Jupiter have hardly any obliquity at all - which means no seasons for them. Venus' obliquity is 177 degrees; it is almost completely upside down. Put another way, it rotates in the opposite direction from Earth. Were there ever to be a break in Venus' stifling cloud layer, native Venusians would see the Sun rise in the west and set in the east! Uranus is another strange character; his obliquity is 97 degrees. Uranus is lying on his side! This leads to some very strange days and seasons. Each pole of Uranus alternates between being in constant sunlight for 42 years, then perpetual darkness for another 42 years. Only a very thin strip along the equator experiences anything like day/night cycles that we experience - and even then the Sun is frequently sitting very low on the horizon. Astronomers aren't entirely certain how Venus and Uranus came to have such extreme obliquities. A leading hypothesis is that both experienced massive collisions at some point in their distant past, essentially knocking them over. A glancing blow from a minor planet isn't the only thing that can change an obliquity. The tilt of our planet's axis is drifting - ever so slightly - all the time. The poles actually trace out a rather complex dance over time scales ranging from minutes to thousands of centuries. Like a spinning top, our planet also wobbles - though it does so very slowly. Over a period of 26,000 years, the poles trace out a giant circle in the sky. Right now, the north pole points pretty close to the star Polaris. 365 Days of Astronomy no May 14th: Diamond Planet Finder Is A Star http://365daysofastronomy.org/2012/05/14/may-14th-diamond-planet-finder-is-a-star/ http://365daysofastronomy.org/2012/05/14/may-14th-diamond-planet-finder-is-a-star/#comments Mon, 14 May 2012 11:00:46 +0000 kortney.hogan http://365daysofastronomy.org/?p=7683 Date: May 14, 2012 Title: Diamond Planet Finder Is A Star Podcaster: Michael Greenwell Links: http://michaelgreenwell.wordpress.com/ and http://exitstageright.wordpress.com/ Description: Last year, after making an enormously publicized discovery astronomer Matthew Bailes used his moment of fame to defend his scientific colleagues and to try to point us in the direction in which we need to be looking. I think he should be applauded for this and we would do well to listen to what he had to say. Bio: Michael Greenwell has worked, at various times, as a university tutor, a barman, a DJ (not a very good one), an office lackey, supermarket worker, president of a small charity, a researcher, a librarian, a volunteer worker in Nepal during the civil war there, and some other things that were too tedious to mention. He blogs here and also runs the animal extinction site Exit Stage Right. Today's Sponsor: "This episode of 365 days of Astronomy is sponsored by 'The Heliochromologist' " "This episode of 365 days of astronomy was sponsored by iTelescope.net - Expanding your horizons in astronomy today. The premier on-demand telescope network, at dark sky sites in Spain, New Mexico and Siding Spring, Australia." Transcript: At the end of last August, you probably read about the scientists who found a planet that is, in their words “certainly crystalline” or in other words, a large…. well… ok…a VERY large diamond…in fact, it is about 4 times the diameter of the Earth. The planet orbits a pulsar, which they referred to as Beyonce on account of the amount of Bling it was showing off. The story got a lot of coverage but one of the scientists involved, Matthew Bailes, did something a couple of weeks later that was rather brave and just as worthy of note - and I think that he should be applauded for it and that we would do well to listen to what he had to say. Specifically, he wrote an article for an Australian website called “The Conversation” in which he used the opportunity the extensive media coverage this discovery gave him to defend climate scientists and try to draw people’s attention to a problem that is ever worsening ie the fact that while the media are happy to report about weird weather on Jupiter or Saturn for example, they show a certain reluctance to talk about Global Weirding and the problems of Climate change here on planet Earth. I’ll quote to you now a slightly shortened version of what he said…

Following the publication of our finding in the journal Science, our research received amazing attention from the world’s media. I was asked by many journalists about the significance of the discovery. If I were honest, I’d have to concede that, although worthy of publication in Science, in the field of astrophysics it isn’t that significant. And yet the diamond planet has been hugely successful in igniting public curiosity about the universe in which we live. Imagine for a minute that, instead of discovering a diamond planet, we’d made a breakthrough in global temperature projections. Let’s say we studied computer models of the influence of excessive greenhouse gases, verified them through observations, then had them peer-reviewed and published in Science. Instead of sitting back and basking in the glory, I suspect we’d find a lot of commentators, many with no scientific qualifications, pouring scorn on our findings. People on the fringe of science would be quoted as opponents of our work, arguing that it was nothing more than a theory yet to be conclusively proven. Before long our credibility and findings would be under serious question. But luckily we’re not climate scientists. It may come as a big surprise to many, but there is actually no difference between how science works in astronomy and climate change – or any other scientific discipline for that matter. We make observations, run simulations, test and propose hypotheses, and undergo peer review of our findings. Of course we all make mistakes. But eventually the prevailing wisdom of the community triumphs and the field advances. It’s wonderful to be a part of that process. But on occasion those from the fringe of the scientific community will push a position that is simply not credible against the weight of evidence. This occurs within any discipline. But it seems it’s only in the field of climate science that such people are given airtime and column inches to espouse their views. Those who want to ignore what’s happening to Earth feel they need to be able to quote “alternative studies”, regardless of the scientific merit of those studies. In all fields of science, papers are challenged and statistics are debated. If there is any basis to these challenges they stand, but if not they fall by the wayside and the field continues to advance. When big theories fall, it isn’t because of business or political pressures – it’s because of the scientific process. Sadly, the same media commentators who celebrate diamond planets without question are all too quick to dismiss the latest peer-reviewed evidence that suggests man-made activities are responsible for changes in concentrations of CO2 in our atmosphere. The scientific method is universal. If we selectively ignore it in certain disciplines, we do so at our peril.

"Should the free precession be accepted as the correct explanation of the phenomena, it will give an important tool to study white dwarf equations of state. The theory of compact objects predicts certain relations between the spin and precession periods, and our finding provides a good test for the theory and establishes a qualitative model to be explored both theoretically and observationally. Detection of precession can become a powerful tool in searching for the internal properties of compact stars, which would be otherwise inaccessible for us. Combined with other methods to estimate masses and density of the WDs in CVs, the precession period will help to refine these values, which in turn, allows for testing and proving the theory for the precession of compact stars and may allow for further advances in our knowledge of the structure of WDs and the influence of accretion on them."

Some interesting things were also observed in the quiescent state prompting additional scrutiny during this year's season of the longer term behaviour of the system when at quiescence. It has been great to be a part of the wonderful science research that is still ongoing. Its all part of the great science you can do as a part of any number of citizen science initiatives. The AAVSO and Variable Stars South have many and varied research projects just like this one where you can play a significant part in gathering the data and working with professional astronomers. It was great working with such professional people ably lead by Vitaly and George Sjoberg. Participation in campaigns like this is a great way to get to know other astronomers, and build your credibility as a capable amateur astronomer. End of podcast: 365 Days of Astronomy ===================== The 365 Days of Astronomy Podcast is produced by the Astrosphere New Media Association. Audio post-production by Preston Gibson. Bandwidth donated by libsyn.com and wizzard media. Web design by Clockwork Active Media Systems. You may reproduce and distribute this audio for non-commercial purposes. Please consider supporting the podcast with a few dollars (or Euros!). Visit us on the web at 365DaysOfAstronomy.org or email us at info@365DaysOfAstronomy.org. Until tomorrow...goodbye.]]> http://365daysofastronomy.org/2012/05/10/may-10th-twinkle-twinkle-little-star-how-i-wonder-fs-aur/feed/ 0 podcast iya 365 Date: May 10, 2012 - Title: Twinkle Twinkle little star ...... How I wonder FS Aur? - Podcaster: Peter Lake - Organization: AARTScope Blog - Links: http://aartscope.blogspot.com http://vitaly.neustroev.net/research/observing-campaigns/ http://www. Date: May 10, 2012 Title: Twinkle Twinkle little star ...... How I wonder FS Aur? Podcaster: Peter Lake Organization: AARTScope Blog Links: http://aartscope.blogspot.com http://vitaly.neustroev.net/research/observing-campaigns/ http://www.twitter.com/fs_Aur http://www.aavso.org Description: FS Aur is one of the most strangest and erratic variable Stars. Peter Lake reports on the data collected as part of the broader work with Dr Vitaly Neustroev of the Oulu University Finland and discusses the past two seasons of observations. Peter Lake is an Amateur Astronomer from Melbourne Australia and regularly discusses how people can be involved in citizen science and observation programs. Bio: Peter Lake is an amateur Astronomer from Melbourne, Australia, a member of Variable Stars South and the AAVSO and he owns and operates a 0.5m Planewave CDK Telescope at New Mexico skies, which is affiliated to iTelescope.net. Peter has been a participant in citizen science and recovered asteroid 2000 EV70 during the Spacewatch FMO program. More recently Peter has been actively involved in the study of cataclysmic variable star FS Aur, and followup exoplanet observations on Kepler targets of interest. Sponsor: "This episode of 365 days of astronomy is sponsored with thanks to all non-US contributors for showing us that the night sky is something we can all share." "Additional sponsorship for this episode of 365 days of astronomy was provided by iTelescope.net - Expanding your horizons in astronomy today. The premier on-demand telescope network, at dark sky sites in Spain, New Mexico and Siding Spring, Australia." Transcript: Like duck hunting, Variable Stars have their "Seasons" also. A season being where the variable star in question is in the optimal position for "shooting with CCDs" ie observable for most of the night, during this time ideally it can be visible for as many as 6-7 hours per night. FS Aur is a Cataclysmic Variable is now low in the west at sunset at the close of an intensive second season. So I though it would be good to review these past two seasons, before once again, it comes around for observations in the next northern winter. FS Aur is one of the strangest and complex objects in the extensive variable star family. It is thought to be a magnetic white dwarf and red giant binary Star with a third object acting on it in a circumbinary orbit. (Tovmassian et al., 2010) Back in 2010 there was a sporadic and incomplete light curve and astronomers wanted answers. When they want answers they often leverage the collective effort of the American Association of Variable Star Observers (AAVSO), to muscle up some more observations and data. FS Aur has a number of photometric and spectroscopic cycles going on. On top of this it goes into outburst about every 12-15 days. The outburst duration is so short (2-3 days) it has been regularly missed in the past - so in the 2010/11 season Dr Neustroev rallied a special effort. For the first time, members of the AAVSO mapped the entire outburst cycle, a good number of times. Dr Vitaly Neustroev is the University Researcher (Yliopistotutkija) at the University of Oulu, Finland and he is a key researcher on FS Aur, working hard to better understand its erratic behaviour. Visit the observing campaign page here, and also follow on (Twitter). I like following Cataclysmic Variables, after catching Simostronomy fever, and I have been a regular on FS Aur since Dr Neustroev's call to action. During the campaign FS Aur has been dancing away with a little periodic wobble at about 15.9 with the odd subtle change in brightness, then it goes really dull to 16.2 then literally within 24-36 hours it pops up to magnitude about Mag 14. As an amateur astronomer I am always careful to point out that I'm not qualified to say how or why, but I can tell you when, where and how bright! So what is going on with FS Aur - Dr Neustroev describes it this way: 365 Days of Astronomy no May 9th: Astronomy Word of the Week: Nova http://365daysofastronomy.org/2012/05/09/may-9th-astronomy-word-of-the-week-nova/ http://365daysofastronomy.org/2012/05/09/may-9th-astronomy-word-of-the-week-nova/#comments Wed, 09 May 2012 11:00:09 +0000 kortney.hogan http://365daysofastronomy.org/?p=7650 Date: May 9, 2012 Title: Astronomy Word of the Week: Nova Podcaster: Dr. Christopher Crockett Organization: United States Naval Observatory Links: http://christophercrockett.com http://astrowow.wordpress.com/ Description: Why do once invisible stars suddenly flare up and then slowly fade from view? The astronomy word of the week is "nova". Bio: Dr. Christopher Crockett is an astronomer at the United States Naval Observatory in Flagstaff, Arizona. His research involves searching for planets around very young stars (“only” a few million years old). It is hoped that the results from this research will help constrain models of planet formation and lead to a better understanding of where, when, and how often planets form. Chris is also passionate about astronomy outreach and education and will talk for hours about the Universe if you let him. Sponsors: Sponsorship for this episode of "365 days of Astronomy" is donated anonymously and dedicated to the men and women of NASA who strive to turn science fiction into science reality. Additional sponsorship for this episode has been provided by iTelescope.net - Expanding your horizons in astronomy today. The premier on-demand telescope network, at dark sky sites in Spain, New Mexico and Siding Spring, Australia. Transcript: In 1572, Danish astronomer Tycho Brahe, along with observers around the world, noticed a new star in the constellation Casseiopeia. Rivaling Venus as the brightest object in the night sky after the Moon, the unexpected guest remained visible for nearly two years before fading from view. The appearance of a new star was nothing short of revolutionary; astronomers long agreed that the celestial sphere was unchanging. A transient star challenged this assumption and suggested that the heavens were perhaps more dynamic than originally thought. The celestial intruder came to be known as a "nova" - after Tycho Brahe's extensive manuscript on the phenomenon - where he referred to the object simply by the latin term for a new star: "stella nova". While no one could have known it at the time, the new star was actually not new at all but rather a very old star experiencing a cataclysmic event. Most of the stars in the sky are not singular, like our Sun, but rather members of binary star systems - two stars locked in orbit around one another. Of this pair, one star is often more massive than its companion and therefore burns through its nuclear fuel at a faster rate. The heavier star reaches the end of its life before its sibling. When it does, the star inflates to become a red giant and sheds its outer layers into space leaving behind the hot, dense stellar core. The naked core, known as a "white dwarf", continues to orbit its stellar neighbor while taking the next few billion years to passively cool from a white-hot 100,000 degrees. In the case of close binary pairs, the white dwarf can actually siphon matter off of its companion. The intermingled gravitational fields of the two stars builds a bridge of predominately hydrogen gas spanning the distance between them. Gas from the still active star flows through this gravitational funnel and spills on to the surface of the white dwarf. The mass of the white dwarf controls the rate of mass accretion; if the rate is high enough, then something quite spectacular can happen. White dwarfs are an example of a rather exotic type of matter that physicists call "degenerate". Most gasses expand when you heat them up: the increasing temperature causes the molecules to zip around faster which in turn increases the gas pressure. At extreme densities - like those seen in the cores of stars - the gas behaves rather peculiarly. The pressure is no longer a slave to temperature: turn up the heat and the gas does not expand. This counterintuitive behavior is crucial to what happens next on the white dwarf's surface. As hydrogen from the donor star comes crashing down, the crushing force of gravity compresses it into a degenerate state and the intense radiation heats the gas to many millions of degrees. But having now obtained the properties of a degenerate gas, the newly acquired hydrogen shell doesn't expand in response to the rapid heating, but holds its pressure steady. And now things get interesting. At temperatures exceeding 16 million degrees Celsius, conditions on the surface mimic those deep in the cores of stars and a thermonuclear explosion is the result. Hydrogen is rapidly fused into helium and the resulting release of energy blows the outer hydrogen shell off the surface of the white dwarf at speeds exceeding ten million kilometers per hour. In mere days, the white dwarf can increase its brightness by 100,000 times. It can then take months - or in some cases years - for the star to slowly fade from view. Our Milky Way Galaxy experiences several dozen novae each year, only about ten of which are visible from Earth. A few are even visible to the naked eye. The most recent nova to be seen without the aid of binoculars or telescopes did so in the constellation Scorpius, reaching its peak brightness on February 17, 2007. Even more rare are what astronomers call "recurrent nova". Once the white dwarf has blown the hydrogen shell into space, the gas can slowly start building up again. These are novae that flare up repeatedly, sometimes once a year, sometimes once every couple of decades. In our whole galaxy, only ten novae are known to be recurrent. In the centuries since the new star of 1572, astronomers have come to realize that the event which gave novae their name was not what we know now as a nova. Up until early in the 20th century, a nova referred to any rapid brightening of a star. But there are many reasons stars suddenly flare into view. What Tycho saw was actually something far more powerful - a type of, aptly named, supernova. The supernova of 1572 was not the result of a flash of hydrogen burning on a white dwarf shell, but rather was caused by the complete detonation of a white dwarf. By stealing gas from a nearby companion slowly enough, the progenitor of the supernova delayed a nova flash while gradually increasing its temperature and pressure and eventually igniting hydrogen fusion throughout the interior of the once dead stellar core. With out the counterbalancing force of the rest of the star to throttle these reactions, the now violently active core obliterated itself in one of the most powerful explosions the Universe can produce. The event of 1572 ushered in a new era of astronomy, one in which the constancy of the celestial sphere could no longer be assumed. Novae - and their more powerful supernovae cousins - are constant reminders that we, in fact, live in a highly dynamic and energetic Universe. End of podcast: 365 Days of Astronomy ===================== The 365 Days of Astronomy Podcast is produced by the Astrosphere New Media Association. Audio post-production by Preston Gibson. Bandwidth donated by libsyn.com and wizzard media. Web design by Clockwork Active Media Systems. You may reproduce and distribute this audio for non-commercial purposes. Please consider supporting the podcast with a few dollars (or Euros!). Visit us on the web at 365DaysOfAstronomy.org or email us at info@365DaysOfAstronomy.org. Until tomorrow...goodbye.]]> http://365daysofastronomy.org/2012/05/09/may-9th-astronomy-word-of-the-week-nova/feed/ 0 podcast iya 365 Date: May 9, 2012 - Title: Astronomy Word of the Week: Nova - Podcaster: Dr. Christopher Crockett - Organization: United States Naval Observatory - Links: http://christophercrockett.com http://astrowow.wordpress.com/ - Date: May 9, 2012 Title: Astronomy Word of the Week: Nova Podcaster: Dr. Christopher Crockett Organization: United States Naval Observatory Links: http://christophercrockett.com http://astrowow.wordpress.com/ Description: Why do once invisible stars suddenly flare up and then slowly fade from view? The astronomy word of the week is "nova". Bio: Dr. Christopher Crockett is an astronomer at the United States Naval Observatory in Flagstaff, Arizona. His research involves searching for planets around very young stars (“only” a few million years old). It is hoped that the results from this research will help constrain models of planet formation and lead to a better understanding of where, when, and how often planets form. Chris is also passionate about astronomy outreach and education and will talk for hours about the Universe if you let him. Sponsors: Sponsorship for this episode of "365 days of Astronomy" is donated anonymously and dedicated to the men and women of NASA who strive to turn science fiction into science reality. Additional sponsorship for this episode has been provided by iTelescope.net - Expanding your horizons in astronomy today. The premier on-demand telescope network, at dark sky sites in Spain, New Mexico and Siding Spring, Australia. Transcript: In 1572, Danish astronomer Tycho Brahe, along with observers around the world, noticed a new star in the constellation Casseiopeia. Rivaling Venus as the brightest object in the night sky after the Moon, the unexpected guest remained visible for nearly two years before fading from view. The appearance of a new star was nothing short of revolutionary; astronomers long agreed that the celestial sphere was unchanging. A transient star challenged this assumption and suggested that the heavens were perhaps more dynamic than originally thought. The celestial intruder came to be known as a "nova" - after Tycho Brahe's extensive manuscript on the phenomenon - where he referred to the object simply by the latin term for a new star: "stella nova". While no one could have known it at the time, the new star was actually not new at all but rather a very old star experiencing a cataclysmic event. Most of the stars in the sky are not singular, like our Sun, but rather members of binary star systems - two stars locked in orbit around one another. Of this pair, one star is often more massive than its companion and therefore burns through its nuclear fuel at a faster rate. The heavier star reaches the end of its life before its sibling. When it does, the star inflates to become a red giant and sheds its outer layers into space leaving behind the hot, dense stellar core. The naked core, known as a "white dwarf", continues to orbit its stellar neighbor while taking the next few billion years to passively cool from a white-hot 100,000 degrees. In the case of close binary pairs, the white dwarf can actually siphon matter off of its companion. The intermingled gravitational fields of the two stars builds a bridge of predominately hydrogen gas spanning the distance between them. Gas from the still active star flows through this gravitational funnel and spills on to the surface of the white dwarf. The mass of the white dwarf controls the rate of mass accretion; if the rate is high enough, then something quite spectacular can happen. White dwarfs are an example of a rather exotic type of matter that physicists call "degenerate". Most gasses expand when you heat them up: the increasing temperature causes the molecules to zip around faster which in turn increases the gas pressure. At extreme densities - like those seen in the cores of stars - the gas behaves rather peculiarly. The pressure is no longer a slave to temperature: turn up the heat and the gas does not expand. This counterintuitive behavior is crucial to what happens next on the white dwarf's surface. As hydrogen from the donor star comes crashing down, 365 Days of Astronomy no May 8th: What is Black http://365daysofastronomy.org/2012/05/08/may-8th-what-is-black/ http://365daysofastronomy.org/2012/05/08/may-8th-what-is-black/#comments Tue, 08 May 2012 11:00:41 +0000 kortney.hogan http://365daysofastronomy.org/?p=7646 Date: May 8, 2012 Title: What is Black Podcaster: Rob Sparks & Dr. Steven Pompea Organization: NOAO Links: www.noao.edu Description: Most people think of black as a color, but black is really the absence of light. Truly black surfaces reflect almost none of the light that falls on them. In this podcast, Dr. Stephen Pompea discusses black surface, how they are produced and why they are important in astronomy and other sciences. Bio: Rob Sparks is a science education specialist in the EPO group at NOAO and works on the Galileoscope project (www.galileoscope.org), providing design, dissemination and professional development. He also pens a great blog at halfastro.wordpress.com. Dr. Stephen Pompea did his undergraduate work in physics, space physics, and astronomy at Rice University, his Master’s work in physics teaching at Colorado State University, and his Ph.D. in astronomy at the University of Arizona. He is currently the manager of the Education and Public Outreach Group at the National Optical Astronomy Observatory. Sponsor: This episode of the 365 Days of Astronomy podcast is sponsored by the National Optical Astronomy Observatory. NOAO is a US national research and development center for ground-based nighttime astronomy. We provide astronomers access to world-class observing facilities on a peer-reviewed basis. Our mission is to engage in programs to develop the next generation of telescopes, instruments, and software tools necessary to enable exploration and investigation through the observable Universe. For information on observing proposals or our public programs, please visit www.noao.edu for more information. "This episode has also been sponsored by the Lake County Astronomical Society: Celebrating 30 years of stellar service to members and the public." Transcript: *** Transcript coming soon. *** End of podcast: 365 Days of Astronomy ===================== The 365 Days of Astronomy Podcast is produced by the Astrosphere New Media Association. Audio post-production by Preston Gibson. Bandwidth donated by libsyn.com and wizzard media. Web design by Clockwork Active Media Systems. You may reproduce and distribute this audio for non-commercial purposes. Please consider supporting the podcast with a few dollars (or Euros!). Visit us on the web at 365DaysOfAstronomy.org or email us at info@365DaysOfAstronomy.org. Until tomorrow...goodbye.]]> http://365daysofastronomy.org/2012/05/08/may-8th-what-is-black/feed/ 0 podcast iya 365 Date: May 8, 2012 - Title: What is Black - Podcaster: Rob Sparks & Dr. Steven Pompea - Organization: NOAO - Links: www.noao.edu - Description: Most people think of black as a color, but black is really the absence of light. Date: May 8, 2012 Title: What is Black Podcaster: Rob Sparks & Dr. Steven Pompea Organization: NOAO Links: www.noao.edu Description: Most people think of black as a color, but black is really the absence of light. Truly black surfaces reflect almost none of the light that falls on them. In this podcast, Dr. Stephen Pompea discusses black surface, how they are produced and why they are important in astronomy and other sciences. Bio: Rob Sparks is a science education specialist in the EPO group at NOAO and works on the Galileoscope project (www.galileoscope.org), providing design, dissemination and professional development. He also pens a great blog at halfastro.wordpress.com. Dr. Stephen Pompea did his undergraduate work in physics, space physics, and astronomy at Rice University, his Master’s work in physics teaching at Colorado State University, and his Ph.D. in astronomy at the University of Arizona. He is currently the manager of the Education and Public Outreach Group at the National Optical Astronomy Observatory. Sponsor: This episode of the 365 Days of Astronomy podcast is sponsored by the National Optical Astronomy Observatory. NOAO is a US national research and development center for ground-based nighttime astronomy. We provide astronomers access to world-class observing facilities on a peer-reviewed basis. Our mission is to engage in programs to develop the next generation of telescopes, instruments, and software tools necessary to enable exploration and investigation through the observable Universe. For information on observing proposals or our public programs, please visit www.noao.edu for more information. "This episode has also been sponsored by the Lake County Astronomical Society: Celebrating 30 years of stellar service to members and the public." Transcript: *** Transcript coming soon. *** End of podcast: 365 Days of Astronomy ===================== The 365 Days of Astronomy Podcast is produced by the Astrosphere New Media Association. Audio post-production by Preston Gibson. Bandwidth donated by libsyn.com and wizzard media. Web design by Clockwork Active Media Systems. You may reproduce and distribute this audio for non-commercial purposes. Please consider supporting the podcast with a few dollars (or Euros!). Visit us on the web at 365DaysOfAstronomy.org or email us at info@365DaysOfAstronomy.org. Until tomorrow...goodbye. 365 Days of Astronomy no May 7th: The Late Heavy Bombardment — an Extended Version? http://365daysofastronomy.org/2012/05/08/may-8th-what-is-black/ http://365daysofastronomy.org/2012/05/08/may-8th-what-is-black/#comments Tue, 08 May 2012 11:00:41 +0000 kortney.hogan http://365daysofastronomy.org/?p=7646 Date: May 8, 2012 Title: What is Black Podcaster: Rob Sparks & Dr. Steven Pompea Organization: NOAO Links: www.noao.edu Description: Most people think of black as a color, but black is really the absence of light. Truly black surfaces reflect almost none of the light that falls on them. In this podcast, Dr. Stephen Pompea discusses black surface, how they are produced and why they are important in astronomy and other sciences. Bio: Rob Sparks is a science education specialist in the EPO group at NOAO and works on the Galileoscope project (www.galileoscope.org), providing design, dissemination and professional development. He also pens a great blog at halfastro.wordpress.com. Dr. Stephen Pompea did his undergraduate work in physics, space physics, and astronomy at Rice University, his Master’s work in physics teaching at Colorado State University, and his Ph.D. in astronomy at the University of Arizona. He is currently the manager of the Education and Public Outreach Group at the National Optical Astronomy Observatory. Sponsor: This episode of the 365 Days of Astronomy podcast is sponsored by the National Optical Astronomy Observatory. NOAO is a US national research and development center for ground-based nighttime astronomy. We provide astronomers access to world-class observing facilities on a peer-reviewed basis. Our mission is to engage in programs to develop the next generation of telescopes, instruments, and software tools necessary to enable exploration and investigation through the observable Universe. For information on observing proposals or our public programs, please visit www.noao.edu for more information. "This episode has also been sponsored by the Lake County Astronomical Society: Celebrating 30 years of stellar service to members and the public." Transcript: *** Transcript coming soon. *** End of podcast: 365 Days of Astronomy ===================== The 365 Days of Astronomy Podcast is produced by the Astrosphere New Media Association. Audio post-production by Preston Gibson. Bandwidth donated by libsyn.com and wizzard media. Web design by Clockwork Active Media Systems. You may reproduce and distribute this audio for non-commercial purposes. Please consider supporting the podcast with a few dollars (or Euros!). Visit us on the web at 365DaysOfAstronomy.org or email us at info@365DaysOfAstronomy.org. Until tomorrow...goodbye.]]> http://365daysofastronomy.org/2012/05/08/may-8th-what-is-black/feed/ 0 podcast iya 365 Date: May 8, 2012 - Title: What is Black - Podcaster: Rob Sparks & Dr. Steven Pompea - Organization: NOAO - Links: www.noao.edu - Description: Most people think of black as a color, but black is really the absence of light. Date: May 8, 2012 Title: What is Black Podcaster: Rob Sparks & Dr. Steven Pompea Organization: NOAO Links: www.noao.edu Description: Most people think of black as a color, but black is really the absence of light. Truly black surfaces reflect almost none of the light that falls on them. In this podcast, Dr. Stephen Pompea discusses black surface, how they are produced and why they are important in astronomy and other sciences. Bio: Rob Sparks is a science education specialist in the EPO group at NOAO and works on the Galileoscope project (www.galileoscope.org), providing design, dissemination and professional development. He also pens a great blog at halfastro.wordpress.com. Dr. Stephen Pompea did his undergraduate work in physics, space physics, and astronomy at Rice University, his Master’s work in physics teaching at Colorado State University, and his Ph.D. in astronomy at the University of Arizona. He is currently the manager of the Education and Public Outreach Group at the National Optical Astronomy Observatory. Sponsor: This episode of the 365 Days of Astronomy podcast is sponsored by the National Optical Astronomy Observatory. NOAO is a US national research and development center for ground-based nighttime astronomy. We provide astronomers access to world-class observing facilities on a peer-reviewed basis. Our mission is to engage in programs to develop the next generation of telescopes, instruments, and software tools necessary to enable exploration and investigation through the observable Universe. For information on observing proposals or our public programs, please visit www.noao.edu for more information. "This episode has also been sponsored by the Lake County Astronomical Society: Celebrating 30 years of stellar service to members and the public." Transcript: *** Transcript coming soon. *** End of podcast: 365 Days of Astronomy ===================== The 365 Days of Astronomy Podcast is produced by the Astrosphere New Media Association. Audio post-production by Preston Gibson. Bandwidth donated by libsyn.com and wizzard media. Web design by Clockwork Active Media Systems. You may reproduce and distribute this audio for non-commercial purposes. Please consider supporting the podcast with a few dollars (or Euros!). Visit us on the web at 365DaysOfAstronomy.org or email us at info@365DaysOfAstronomy.org. Until tomorrow...goodbye. 365 Days of Astronomy no 365 Days of Astronomy http://365daysofastronomy.org An astronomy podcast every day, all year Wed, 16 May 2012 11:00:41 +0000 en hourly 1 http://wordpress.org/?v=3.1 An astronomy podcast every day, all year 365 Days of Astronomy no An astronomy podcast every day, all year 365 Days of Astronomy http://365daysofastronomy.org/wp-content/plugins/powerpress/rss_default.jpg http://365daysofastronomy.org May 16th: GPS http://365daysofastronomy.org/2012/05/16/may-16th-gps/ http://365daysofastronomy.org/2012/05/16/may-16th-gps/#comments Wed, 16 May 2012 11:00:41 +0000 kortney.hogan http://365daysofastronomy.org/?p=7689 Date: May 16, 2012 Title: GPS Podcaster: Steve Nerlich Organization: Cheap Astronomy Links: www.cheapastro.com Description: Cheap Astronomy once again demonstrates that pretty much everything in life has a connection to astronomy. Bio: Cheap Astronomy offers an educational website because in space no-one can hear you podcast. Today's Sponsor: "This episode of 365 days of Astronomy" is sponsored by the Lake County Astronomical Society: Celebrating 30 years of stellar service to members and the public." Additional sponsorship for this episode has also been provided by iTelescope.net - Expanding your horizons in astronomy today. The premier on-demand telescope network, at dark sky sites in Spain, New Mexico and Siding Spring, Australia. Transcript: Hi this is Steve Nerlich from Cheap Astronomy www.cheapastro.com and this is GPS OK – If you don’t have one, you know someone who does, so let’s skip the introductions and get straight down to the astronomy. A standard GPS configuration is a constellation of 24 GPS satellites. The satellites are all at an altitude of 20,200 km with an orbital period of 11 hours and 58 minutes – which means they do exactly 2 orbits for each time the Earth spins once on its axis. Four satellites each follow six orbital planes separated by 60 degrees which surround the Earth in an (airquotes) ‘birdcage’ of criss-crossing orbits. There a link to the relevant Wikipedia article from the Cheap Astronomy podcast page which has a nice animation of a GPS satellite constellation. At last count, there were actually 31 actively transmitting GPS satellites – with these extra number increasing location accuracy and redundancy. There’s been some recent media regarding a growing risk of dropping below the minimum 24 active satellites required to make GPS work effectively, but it remains to be seen if this risk will be realised in the face of the increasing economic importance of maintaining a working GPS system. A GPS satellite broadcasts a signal indicating where it is and the time the signal was broadcast – your receiver then determines, from the time it receives that signal, the distance travelled by the signal, knowing that, being a radio transmission, the signal travels at the speed of light. By making just four calculations from four satellites in the sky, your GPS receiver can then establish its position with respect to latitude, longitude and altitude. It’s all about the conjunction of spheres. Imagine one satellite broadcasting a radio signal. If you pick up that signal and determine it’s a 100 km away, all you really know is that you are somewhere on a surface of a sphere with a 100 km radius that has the satellite at its centre. If there’s two such satellites then you’ll know you are somewhere on the circumference of a circle representing the plane where the two spheres of radio broadcast overlap. Introduce a third satellite and you can narrow down your location to just two points in space which are the points where two differently orientated circle circumferences intersect. Potentially this may be enough to roughly determine your position since you can anticipate you will be on the one of those two points corresponding to the surface of the Earth. But for strictest accuracy – including accuracy in determining your altitude above sea level, the signal from a fourth satellite is required. And that is the idea of the constellation of GPS satellites. Keeping 24 satellites moving in the same orbit, tracing a birdcage of divergent paths around the globe ensures there will always be four satellites in the sky wherever you happen to be on Earth. Now when I say GPS satellites just have to broadcast where they are – actually knowing where they are is a whole separate operation, While the orbital period is predictable, knowing at what point they are on that orbit requires some very accurate time keeping – for which reason each satellite has an atomic clock. Nonetheless, even this isn’t enough, as the orbital paths of the satellites are subject to slight shifting due to the gravitational influence of the Sun and the Moon. To keep track of these changes the satellites are monitored from a fixed, known location on the Earth’s surface – a function currently managed by the 50th Space Wing of the US Airforce Space Command – seriously. Now, given that your GPS receiver is working out its distance from each of four satellites based solely on the time lag of a signal moving at the speed of light from a satellite just over 20,000 kilometres away – there is considerable potential for a margin of error that could see you driving over the embankment into a river when that sexy voice says ‘turn left now’. There are a range of methods to deal with various sources of error. Firstly your GPS receiver carries an electronic almanac of which satellite should be where since confusion can arise when the satellite radio signals get reflected off surroundings, such as tall buildings. This electronic almanac is constructed from calibration data received from the GPS satellites, although these data are generally relayed from a ground-based source – such as Airforce Space Command. The almanac helps your receiver distinguish between garbage signals and genuine GPS signals. The receiver also receives time checks from the satellites since, most GPS receivers determine time from a cheap (not that there’s anything wrong with that) quartz clock rather than the ultra-accurate atomic clocks of the satellites. Clock error is probably the biggest potential source of GPS error, which is why, even though you could almost get away with determining your position from just 3 satellites, it is the fourth reading (which we might call quadrangulation) that ensures the poorer accuracy of the GPS receiver’s clock is effectively accounted for. Interestingly, there’s also relativistic effects to account for, since the satellites move in a weaker gravity field (meaning by general relativity their clocks run faster), and they also move at speed relative to the surface of the Earth (meaning by special relativity their clocks run slower). It turns out that the nett effect is that the satellites’ clocks run about 38 microseconds per day faster than they would at the Earth’s surface. To account for this, the clocks are actually set to run at a slightly lower rate, to keep pace with clocks running on the Earth’s surface. In the world of atomic clocks, various time keeping callibrations are also required to account for changes in the rotation of the Earth – which is influenced by the tidal drag of the Moon , the inertia of the Earth’s molten interior and even the melting of glaciers. Overall, the Earth’s rotation is slowing, leading to a lengthening of a solar day. Consequently a leap second must be introduced to atomic timepieces which measure Universal Coordinated Time (known as UTC – because of the French). In fact, a leap second is required to be added to UTC every 18 months or so because each year (on average) the length of a solar day increases by about 0.002 seconds. The atomic clocks of GPS satellites were aligned to UTC in 1980 – but as of 2009, these atomic clocks in orbit now vary by 19 seconds and to keep it simple we just say they are running at GPS time. Various under-the-hood adjustments are made along the way so that your GPS receiver can tell you the local time wherever you happen to be – as well as telling you where you are of course to within… well, within 10 metres is the general benchmark, although this takes a few minutes to establish after the unit is turned on and the accuracy will degrade with tall trees or buildings around. So, you know, it’s a guide – not an absolute – it’s still a good idea to keep one eye on the road. Thanks for listening. This is Steve Nerlich from Cheap Astronomy, www.cheapastro.com. Cheap Astronomy offers an educational website where you can’t put a price on space. No ads, no profit, just good science. Bye. End of podcast: 365 Days of Astronomy ===================== The 365 Days of Astronomy Podcast is produced by the New Media Working Group of the International Year of Astronomy 2009. Audio post-production by Preston Gibson. Bandwidth donated by libsyn.com and wizzard media. Web design by Clockwork Active Media Systems. You may reproduce and distribute this audio for non-commercial purposes. Please consider supporting the podcast with a few dollars (or Euros!). Visit us on the web at 365DaysOfAstronomy.org or email us at info@365DaysOfAstronomy.org. Until tomorrow...goodbye.]]> http://365daysofastronomy.org/2012/05/16/may-16th-gps/feed/ 0 podcast iya 365 Date: May 16, 2012 - Title: GPS Podcaster: Steve Nerlich - Organization: Cheap Astronomy - Links: www.cheapastro.com - Description: Cheap Astronomy once again demonstrates that pretty much everything in life has a connection to astronomy. - Date: May 16, 2012 Title: GPS Podcaster: Steve Nerlich Organization: Cheap Astronomy Links: www.cheapastro.com Description: Cheap Astronomy once again demonstrates that pretty much everything in life has a connection to astronomy. B... 365 Days of Astronomy no May 15th: Astronomy Word of the Week: Obliquity http://365daysofastronomy.org/2012/05/15/may-15th-astronomy-word-of-the-week-obliquity/ http://365daysofastronomy.org/2012/05/15/may-15th-astronomy-word-of-the-week-obliquity/#comments Tue, 15 May 2012 11:00:14 +0000 kortney.hogan http://365daysofastronomy.org/?p=7687 Date: May 15, 2012 Title: Astronomy Word of the Week: Obliquity Podcaster: Dr. Christopher Crockett Organization: United States Naval Observatory Links: http://christophercrockett.com http://astrowow.wordpress.com/ Description: The tilt of our planet is about much more than the seasons. The astronomy word of the week is "obliquity". Bio: Dr. Christopher Crockett is an astronomer at the United States Naval Observatory in Flagstaff, Arizona. His research involves searching for planets around very young stars (“only” a few million years old). It is hoped that the results from this research will help constrain models of planet formation and lead to a better understanding of where, when, and how often planets form. Chris is also passionate about astronomy outreach and education and will talk for hours about the Universe if you let him. Today's Sponsor: "This episode of 365 days of Astronomy" is sponsored by iTelescope.net - Expanding your horizons in astronomy today. The premier on-demand telescope network, at dark sky sites in Spain, New Mexico and Siding Spring, Australia. This episode has also been sponsored by Lake County Astronomical Society: Celebrating 30 years of stellar service to members and the public. Transcript: The planet you're standing on is not very steady. She bobs and wobbles, ducks and weaves, as she makes her annual trek around the Sun. Our home constantly struggles with forces both external and internal; the Sun, the Moon, and the planets tug her back and forth while shifting masses within force her to constantly find new balance. The tilt of our planet's axis - what astronomers call its obliquity - is one measure of this interplanetary tug-of-war. Obliquity measures how far over a planet or moon is tipped relative to its orbit; in the Earth's case, it's about 23 degrees. We feel the obliquity in the changing seasons. In June, the north pole is tipped towards the Sun. The northern hemisphere experiences longer days and more direct sunlight giving us warm summer days. In December, the north pole is tipped away from the Sun and everyone above the equator experiences the bitter chill of winter as the days get shorter and the sunlight reaches us more obliquely. The other planets in our solar system exhibit a wide range of obliquities. Mars, Saturn, and Neptune are all tipped by roughly the same amount as Earth. Mercury and Jupiter have hardly any obliquity at all - which means no seasons for them. Venus' obliquity is 177 degrees; it is almost completely upside down. Put another way, it rotates in the opposite direction from Earth. Were there ever to be a break in Venus' stifling cloud layer, native Venusians would see the Sun rise in the west and set in the east! Uranus is another strange character; his obliquity is 97 degrees. Uranus is lying on his side! This leads to some very strange days and seasons. Each pole of Uranus alternates between being in constant sunlight for 42 years, then perpetual darkness for another 42 years. Only a very thin strip along the equator experiences anything like day/night cycles that we experience - and even then the Sun is frequently sitting very low on the horizon. Astronomers aren't entirely certain how Venus and Uranus came to have such extreme obliquities. A leading hypothesis is that both experienced massive collisions at some point in their distant past, essentially knocking them over. A glancing blow from a minor planet isn't the only thing that can change an obliquity. The tilt of our planet's axis is drifting - ever so slightly - all the time. The poles actually trace out a rather complex dance over time scales ranging from minutes to thousands of centuries. Like a spinning top, our planet also wobbles - though it does so very slowly. Over a period of 26,000 years, the poles trace out a giant circle in the sky. Right now, the north pole points pretty close to the star Polaris. But over time that will change, and in some epochs it will be pointing at nothing at all. This wobble - or precession - doesn't change the amount of obliquity; it simply changes where in space the poles are pointing. The Moon, however, does tug on our planet's axis. In addition to rotation and precession, the Earth experiences something called nutation. This is a slight rocking of the Earth's axis caused by the changing positions of the Moon, the Sun, and all the other bodies in the solar system. With many players involved, the motion from nutation is fairly complex. The main component nods the planet by a couple hundred meters over a nearly 19 year cycle that is tied to how the Moon's orbit drifts around the Earth. Our planet also has to contend with forces much closer to home. Internal motions of magma, deep sea currents, changing ocean salinity, winds, melting ice sheets, and even earthquakes all conspire to constantly change the distribution of mass within the Earth. The planet responds by continuously shifting its spin axis - an effect known as polar motion. This is a bit different than nutation; it actually changes where on Earth the north and south poles are located. Hard as it may be to fathom, these are not fixed locations on the globe. The drift is very small - centimeters per year - but it does add a complex twist to understanding our planets motion in space. The presence of a large moon is believed to help stabilize our obliquity. The tilt does change by a few degrees over many millions of years, but manages to hold steady at around 20-25 degrees. Mars, conversely, appears to be going through a chaotic evolution in its obliquity. Computer simulations of its stability suggest that, over the past few million years, the Red Planet's tilt has oscillated wildly between zero and sixty degrees which may lead to drastic swings in the environment. Many astrobiologists - scientists who study the evolution and origin of life in a cosmic context - argue that our moon may be an essential ingredient for providing a stable environment within which life could thrive. Does this mean that the existence of complex life and advanced civilizations is dependent on the presence of a large satellite? That's hard to say. It is certainly plausible that our closest neighbor in space has been an indispensable partner in the evolution of our species. I'm continually amazed at how a simple concept - like the tilt of a planet - can actually lead down a labyrinthian path of subtleties. Studying Earth's obliquity, and the obliquity of all the other planets and moons, reveals much about the dynamics of our planet, the interplay of our home and neighboring worlds, and even the often times cataclysmic evolution of the solar system. While the subtleties are far removed from our day-to-day lives, our Earth's position in space actually is inseparable from the human experience. The June solstice is just over a month away. Whether you're bundling up for winter, or heading to the beach for summer, remember: the Earth's obliquity is the reason for the seasons! End of podcast: 365 Days of Astronomy ===================== The 365 Days of Astronomy Podcast is produced by the New Media Working Group of the International Year of Astronomy 2009. Audio post-production by Preston Gibson. Bandwidth donated by libsyn.com and wizzard media. Web design by Clockwork Active Media Systems. You may reproduce and distribute this audio for non-commercial purposes. Please consider supporting the podcast with a few dollars (or Euros!). Visit us on the web at 365DaysOfAstronomy.org or email us at info@365DaysOfAstronomy.org. Until tomorrow...goodbye.]]> http://365daysofastronomy.org/2012/05/15/may-15th-astronomy-word-of-the-week-obliquity/feed/ 0 podcast iya 365 Date: May 15, 2012 - Title: Astronomy Word of the Week: Obliquity Podcaster: Dr. Christopher Crockett - Organization: United States Naval Observatory - Links: http://christophercrockett.com http://astrowow.wordpress.com/ - Date: May 15, 2012 Title: Astronomy Word of the Week: Obliquity Podcaster: Dr. Christopher Crockett Organization: United States Naval Observatory Links: http://christophercrockett.com http://astrowow.wordpress.com/ Description: The tilt of our planet is about much more than the seasons. The astronomy word of the week is "obliquity". Bio: Dr. Christopher Crockett is an astronomer at the United States Naval Observatory in Flagstaff, Arizona. His research involves searching for planets around very young stars (“only” a few million years old). It is hoped that the results from this research will help constrain models of planet formation and lead to a better understanding of where, when, and how often planets form. Chris is also passionate about astronomy outreach and education and will talk for hours about the Universe if you let him. Today's Sponsor: "This episode of 365 days of Astronomy" is sponsored by iTelescope.net - Expanding your horizons in astronomy today. The premier on-demand telescope network, at dark sky sites in Spain, New Mexico and Siding Spring, Australia. This episode has also been sponsored by Lake County Astronomical Society: Celebrating 30 years of stellar service to members and the public. Transcript: The planet you're standing on is not very steady. She bobs and wobbles, ducks and weaves, as she makes her annual trek around the Sun. Our home constantly struggles with forces both external and internal; the Sun, the Moon, and the planets tug her back and forth while shifting masses within force her to constantly find new balance. The tilt of our planet's axis - what astronomers call its obliquity - is one measure of this interplanetary tug-of-war. Obliquity measures how far over a planet or moon is tipped relative to its orbit; in the Earth's case, it's about 23 degrees. We feel the obliquity in the changing seasons. In June, the north pole is tipped towards the Sun. The northern hemisphere experiences longer days and more direct sunlight giving us warm summer days. In December, the north pole is tipped away from the Sun and everyone above the equator experiences the bitter chill of winter as the days get shorter and the sunlight reaches us more obliquely. The other planets in our solar system exhibit a wide range of obliquities. Mars, Saturn, and Neptune are all tipped by roughly the same amount as Earth. Mercury and Jupiter have hardly any obliquity at all - which means no seasons for them. Venus' obliquity is 177 degrees; it is almost completely upside down. Put another way, it rotates in the opposite direction from Earth. Were there ever to be a break in Venus' stifling cloud layer, native Venusians would see the Sun rise in the west and set in the east! Uranus is another strange character; his obliquity is 97 degrees. Uranus is lying on his side! This leads to some very strange days and seasons. Each pole of Uranus alternates between being in constant sunlight for 42 years, then perpetual darkness for another 42 years. Only a very thin strip along the equator experiences anything like day/night cycles that we experience - and even then the Sun is frequently sitting very low on the horizon. Astronomers aren't entirely certain how Venus and Uranus came to have such extreme obliquities. A leading hypothesis is that both experienced massive collisions at some point in their distant past, essentially knocking them over. A glancing blow from a minor planet isn't the only thing that can change an obliquity. The tilt of our planet's axis is drifting - ever so slightly - all the time. The poles actually trace out a rather complex dance over time scales ranging from minutes to thousands of centuries. Like a spinning top, our planet also wobbles - though it does so very slowly. Over a period of 26,000 years, the poles trace out a giant circle in the sky. Right now, the north pole points pretty close to the star Polaris. 365 Days of Astronomy no May 14th: Diamond Planet Finder Is A Star http://365daysofastronomy.org/2012/05/14/may-14th-diamond-planet-finder-is-a-star/ http://365daysofastronomy.org/2012/05/14/may-14th-diamond-planet-finder-is-a-star/#comments Mon, 14 May 2012 11:00:46 +0000 kortney.hogan http://365daysofastronomy.org/?p=7683 Date: May 14, 2012 Title: Diamond Planet Finder Is A Star Podcaster: Michael Greenwell Links: http://michaelgreenwell.wordpress.com/ and http://exitstageright.wordpress.com/ Description: Last year, after making an enormously publicized discovery astronomer Matthew Bailes used his moment of fame to defend his scientific colleagues and to try to point us in the direction in which we need to be looking. I think he should be applauded for this and we would do well to listen to what he had to say. Bio: Michael Greenwell has worked, at various times, as a university tutor, a barman, a DJ (not a very good one), an office lackey, supermarket worker, president of a small charity, a researcher, a librarian, a volunteer worker in Nepal during the civil war there, and some other things that were too tedious to mention. He blogs here and also runs the animal extinction site Exit Stage Right. Today's Sponsor: "This episode of 365 days of Astronomy is sponsored by 'The Heliochromologist' " "This episode of 365 days of astronomy was sponsored by iTelescope.net - Expanding your horizons in astronomy today. The premier on-demand telescope network, at dark sky sites in Spain, New Mexico and Siding Spring, Australia." Transcript: At the end of last August, you probably read about the scientists who found a planet that is, in their words “certainly crystalline” or in other words, a large…. well… ok…a VERY large diamond…in fact, it is about 4 times the diameter of the Earth. The planet orbits a pulsar, which they referred to as Beyonce on account of the amount of Bling it was showing off. The story got a lot of coverage but one of the scientists involved, Matthew Bailes, did something a couple of weeks later that was rather brave and just as worthy of note - and I think that he should be applauded for it and that we would do well to listen to what he had to say. Specifically, he wrote an article for an Australian website called “The Conversation” in which he used the opportunity the extensive media coverage this discovery gave him to defend climate scientists and try to draw people’s attention to a problem that is ever worsening ie the fact that while the media are happy to report about weird weather on Jupiter or Saturn for example, they show a certain reluctance to talk about Global Weirding and the problems of Climate change here on planet Earth. I’ll quote to you now a slightly shortened version of what he said…

Following the publication of our finding in the journal Science, our research received amazing attention from the world’s media. I was asked by many journalists about the significance of the discovery. If I were honest, I’d have to concede that, although worthy of publication in Science, in the field of astrophysics it isn’t that significant. And yet the diamond planet has been hugely successful in igniting public curiosity about the universe in which we live. Imagine for a minute that, instead of discovering a diamond planet, we’d made a breakthrough in global temperature projections. Let’s say we studied computer models of the influence of excessive greenhouse gases, verified them through observations, then had them peer-reviewed and published in Science. Instead of sitting back and basking in the glory, I suspect we’d find a lot of commentators, many with no scientific qualifications, pouring scorn on our findings. People on the fringe of science would be quoted as opponents of our work, arguing that it was nothing more than a theory yet to be conclusively proven. Before long our credibility and findings would be under serious question. But luckily we’re not climate scientists. It may come as a big surprise to many, but there is actually no difference between how science works in astronomy and climate change – or any other scientific discipline for that matter. We make observations, run simulations, test and propose hypotheses, and undergo peer review of our findings. Of course we all make mistakes. But eventually the prevailing wisdom of the community triumphs and the field advances. It’s wonderful to be a part of that process. But on occasion those from the fringe of the scientific community will push a position that is simply not credible against the weight of evidence. This occurs within any discipline. But it seems it’s only in the field of climate science that such people are given airtime and column inches to espouse their views. Those who want to ignore what’s happening to Earth feel they need to be able to quote “alternative studies”, regardless of the scientific merit of those studies. In all fields of science, papers are challenged and statistics are debated. If there is any basis to these challenges they stand, but if not they fall by the wayside and the field continues to advance. When big theories fall, it isn’t because of business or political pressures – it’s because of the scientific process. Sadly, the same media commentators who celebrate diamond planets without question are all too quick to dismiss the latest peer-reviewed evidence that suggests man-made activities are responsible for changes in concentrations of CO2 in our atmosphere. The scientific method is universal. If we selectively ignore it in certain disciplines, we do so at our peril.

"Should the free precession be accepted as the correct explanation of the phenomena, it will give an important tool to study white dwarf equations of state. The theory of compact objects predicts certain relations between the spin and precession periods, and our finding provides a good test for the theory and establishes a qualitative model to be explored both theoretically and observationally. Detection of precession can become a powerful tool in searching for the internal properties of compact stars, which would be otherwise inaccessible for us. Combined with other methods to estimate masses and density of the WDs in CVs, the precession period will help to refine these values, which in turn, allows for testing and proving the theory for the precession of compact stars and may allow for further advances in our knowledge of the structure of WDs and the influence of accretion on them."