365 Days of Astronomy

January 27th: Earth Clones

kortney.hogan — Wed, 27 Jan 2010 11:00:02 +0000

Date: January 27, 2010

Title: Earth Clones

Podcaster: Chris Impey

Links: http://planetquest.jpl.nasa.gov/
http://exoplanet.eu/
http://kepler.nasa.gov/
http://www.chrisimpey.com/

Description: There are over 400 planets know orbiting other star, but most are gas giants like Jupiter and likely to be uninhabitable? How long before we find a clone of the Earth? This podcast talks about the issues involved in detecting terrestrial planets and the likelihood that they will be discovered in the next few years.

Bio: Chris Impey is a University Distinguished Professor and Deputy Head of the Department, in charge of all academic programs. His research interests are observational cosmology, gravitational lensing, and the evolution and structure of galaxies. As a professor, he has won eleven teaching awards, and he has been heavily involved in curriculum and instructional technology development. Impey is a past Vice President of the American Astronomical Society. He has also been an NSF Distinguished Teaching Scholar, a Phi Beta Kappa Visiting Scholar, and the Carnegie Council on Teaching’s Arizona Professor of the Year. Impey has written over thirty popular articles on cosmology and astrobiology and co-authored two introductory textbooks. His first popular book “The Living Cosmos,” was published in 2007 by Random House; his second popular book called “How It Ends,” will be published in 2010 by Norton. He recently was a co-chair of the Education and Public Outreach Study Group for the Astronomy Decadal Survey of the National Academy of Sciences. Impey is a 2009 Fellow of the American Association for the Advancement of Science.

Today's sponsor: This episode of "365 Days of Astronomy" is sponsored by -- no one. We still need sponsors for many days in 2010, so please consider sponsoring a day or two. Just click on the "Donate" button on the lower left side of this webpage, or contact us at signup@365daysofastronomy.org.

Transcript:

365 Days of Astronomy Podcast

January 27, 2010

Chris Impey, Professor, University of Arizona

Welcome. This is a podcast for 365 Days of Astronomy for the year 2010. My name is Chris Impey I'm a professor of astronomy at the University of Arizona. My research is on cosmology but I take a keen interest in Astrobiology, the search for life in the universe. And my topic today is Earth clones - what will it take to find twins of Earth out there in deep space.

As I'm sure you know - the success of exoplanet hunting is phenomenal. In 1995 we knew of no planets beyond the solar system. Now we have over 400. However almost all of those planets are gas giants, Jupiter mass ranging down to Neptune and Uranus mass. Almost certainly they're uninhabitable, we don't think there is life in Jupiter or Saturn's atmosphere. So what's really interesting is pushing down the mass limit towards terrestrial planets so we can find planets that might harbor biology. What will it take to do this?

Simulations and theory give us the expectation that terrestrial planets exist out in space even though we haven't found them yet. The current record holder for a low mass planet beyond the solar system is a planet 1.9 times the mass of Earth. However it's not in the habitable zone of its star. Simulations however suggest that for every gas giant planet that forms at the periphery of a solar nebula there will be a handful of terrestrial planets on orbits much like those of Earth, Venus, and Mars.

If we scale up these numbers to the Milky Way we conclude a phenomenal billion habitable worlds in the Milky Way, including moons of giant planets as well. And possibly a tenth of those or about a hundred million will be planets like the Earth, Earth-clones more or less. That's an amazing amount of habitable real estate in just one galaxy in the universe.

So how do we find such planets, with four hundred in the bag but none of them Earth-like? Well the most direct method, making an image, is the most difficult. The Earth reflects less than a billionth of the light of the Sun, and as seen from afar would be like trying to detect a firefly in the glare of nearby stadium floodlights. Essentially impossible with current technology. So we can't image these planets. Also, the Doppler Effect, which has been most successful in finding almost all of the 400 known exoplanets, runs out of steam when it goes to the low mass planets. By the time we get down to a terrestrial planet, the Doppler shift, the wobble on the star caused by the orbiting planet, is a small enough velocity that it can be confused by turbulent motions in the star atmosphere. Essentially noise from the star itself prohibits us detecting earths with the doppler method.

The method that may work, and we hope it will work, is the eclipse method. Every now and then, seen from the right orientation, a terrestrial planet will pass in front of its parent star dimming it very slightly in proportion to the ratio of the area of the planet to the area of the star.

For an Earth-like planet orbiting a Sun-like star, this dimming is tiny, about one hundreth of a percent. That can't be detected from the Earth. But from space, with the stability of that environment it is possible.

Last year the Kepler spacecraft was launched with the deliberate purpose and agenda of detecting terrestrial planets and Earth clones. Kepler has gone through its early paces and has shown that it has the stability and the sensitivity to detect eclipses by Earth-like planets. It's staring at a region of sky containing over 100,000 stars and it'll stare at it for several years trying to detect the momentary dimming of the star. Remember, it's one hundreth of a percent. Imagine trying to stare at a 100W lightbulb to see if it'd dim by hundreth of a watt. It's a difficult task but Kepler has shown it's up for the job.

We'll have to be patient however. An Earth-like planet in orbit around a Sun-like star will of course transit only once every year. And Kepler will need to see the eclipse recurr maybe twice or three times to be sure it's detected a real planet. That means, we'll have to wait a couple of years before Kepler starts announcing Earths. But they are expected.

Nobody really knows how many Earth-like planets Kepler will find. It could be dozens, or it could be as many as hundreds. Meanwhile, we have to look after Earth 1.0. We're not going anywhere else soon. Even if we find an Earth clone, a place that might be hospitable to life, or a place where we might go and colonize, it's going to be very far away. Most of the stars that Kepler is looking at are dozens, if not hundreds, of light years away. With current technology, that would take hundreds or thousands of years to get to. Even with a space probe, and we have no way of sending humans that far.

Alpha Centauri, it turns out, is the nearest place we might look for a terrestrial planet, only about 4 light years away. Careful work on that double star system may well find Earth-like planets within the next few years. This whole work of finding Earth clones will put into sharper focus the next stage in the search for life in the universe. Because once we start finding places with all the ingredients for life: energy from a star, organic material and liquid water on the surface, it should only be a matter of time before we can detect the signs of life on one of those planets.

This has been 365 Days of Astronomy, and this is Chris Impey signing out. Goodbye.

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.

January 19th: Film Astrophotography

kortney.hogan — Tue, 19 Jan 2010 11:00:00 +0000

Date: January 19, 2010

Title: Film Astrophotography

Podcaster: Zachary Kessin

Description: Find out how you can do wide-field astrophotography on the cheap, and get results like professionals.

Bio: Zachary Kessin is a software engineer with Mytopia in Petach Tikva Israel. He lives in the city of Ariel with his wife and 4 children. Zachary holds a BA in physics from Brandeis university in Waltham Ma. He enjoys observing from Israel's Negev desert.

Transcript:

***Transcript coming soon.***

End of podcast:

January 10th: Annular Eclipse in India

kortney.hogan — Sun, 10 Jan 2010 11:00:04 +0000

Date: January 10, 2010

Title: Annular Eclipse in India

Podcaster: Jay Pasachoff

Organization: Williams College: http://www.williams.edu/astronomy

Working Group on Eclipses of the International Astronomical Union: http://www.eclipses.info

Description: In 2010, there will be two central eclipses of the sun: an annular eclipse on January 15 and a total eclipse on July 11. This podcast discusses the annular eclipse, which will be visible in a path from Africa, including Kenya, across the Indian Ocean, over the Maldive Islands, across the southern tip of India and the northern end of Sri Lanka, and then across parts of Bangladesh and Myanmar. The band of annularity winds up crossing China. A partial solar eclipse will be visible for hundreds of miles to either side of the band of annularity. At the center of the band of annularity, the 92% coverage of the sun's diameter lasts over 10 minutes. Safe solar observing procedures, including a solar filter for direct view or projection methods for indirect view, must be used throughout the annular eclipse, even during annularity, since part of the solar photosphere remains visible.

Bio: Jay Pasachoff, Chair of the International Astronomical Union's Working Group on Eclipses, is Field Memorial Professor of Astronomy at Williams College. He has viewed 49 solar eclipses, and is an expert on both their use for scientific observations and their use for public education. Pasachoff is past president of the International Astronomical Union's Commission on Education and Development. He received the Education Prize of the American Astronomical Society. Pasachoff is the author of textbooks on astronomy and of the Field Guide to the Stars and Planets.

Today's sponsor: This episode of "365 Days of Astronomy" is sponsored by Craig Clark.

Transcript:

This is Jay Pasachoff, I'm the Field Memorial Professor of Astronomy at Williams College in Williamstown, Massachusetts, and the chair of the Working Group on Solar Eclipses of the International Astronomical Union.

There will be two eclipses of the sun in the year 2010. The first is an annular eclipse of the sun that will occur on the 15th of January. An annular eclipse is when the moon is a little further than average away from the earth, in its elliptical orbit around the earth, and its angular size in the sky is therefore slightly smaller than the angular size of the sun. So the moon can be silhouetted against the sun but doesn't cover the sun entirely, and we see a ring, or annulus, of everyday sunlight around the black disk of the moon. This is known as an annular eclipse. It never gets completely dark outside during an annular eclipse, at least not the 92 percent coverage that we will have at this annular eclipse. Sometimes they're close to one hundred percent. Because it doesn't get completely dark, we won't be able to see the solar corona, the diamond ring, or the fantastically interesting and beautiful phenomena that one sees at a total solar eclipse, but still annular eclipses are interesting to see. You have to keep a solar filter on to look through for the whole time. The partial phases that last an hour and a half and the annular phase, which, for this eclipse, lasts, in many places, over ten minutes - very long for an eclipse. The longest total solar eclipse possible is only in the seven minutes, and the ones that are occurring these days are never as long as seven minutes, whereas I will have over ten minutes of annular eclipse at the southern tip of India on the 15th of January, 2010.

One doesn't do a lot of science at annular eclipses usually because you can't see the corona, but there are some things you can do scientifically, including radio observations. In India they have a wonderful radio telescope known as the Giant Metre-wave Radio Telescope. It’s near Pune, which is east of Mumbai, and we're arranging to use it in collaboration with some Indian scientists to observe the sun. In particular, if there are active regions on the sun (and this is by no means certain because we're at a very low minimum in the sun spot cycle), as the moon covers the active region on the surface of the sun, its radio emission diminishes and we can tell very precisely where on the sun these regions are and how big they are. You get two cuts across each region on the sun, one when it's covered and one when it's uncovered, and the two together give you the position very precisely. So we're hoping for an active region on the 15th of January so we can do those radio observations.

I'll be at the very southern tip of India, the cape there, south of Trivandrum. There will be millions of people around; it's a very heavily populated part of India. And it will be very interesting to watch the phenomena, the moon gradually cover the sun over an hour and a half or so, and then the ten minutes on annularity, and then the uncovering at the end. The path of annularity begins in the middle of Africa, comes over Nairobi and Kenya and goes over the Indian Ocean. It then passes the Maldive Islands, which we've heard a lot about recently because they're so low-lying that they'll be some of the first casualties of the continued rising of the oceans from global warming. Then the eclipse hits the southern tip of India and the northern part of Sri Lanka and goes back over the ocean. It will hit a very southern protuberance of Bangladesh and go through Myanmar and into China. That's the path of annularity, a hundred or so kilometers wide, but then for a thousand or so kilometers to either side of that there'll be a partial eclipse, so may tens of millions of people will be in a zone where they will be able to see a partial eclipse. It will be fun to watch but not as dramatic as a total solar eclipse.

The total solar eclipse that will occur in 2010 will be on July 11th, and that won't be seen by very many people at all. It is largely over the Pacific Ocean, where it will cross some normally uninhabited atolls not far from Tahiti, so there'll be some ships there and some few expeditions out of Tahiti to see that. The major land in the way is a very unusual island, Easter Island. It's in the middle of the Pacific, some 4000 miles west of the coast of Chile, and it is part of Chile. At sunset the eclipse reaches the Patagonia region of Chile very low in the sky with very poor weather forecasts at that time in Chilean winter, so there isn't a good possibility of seeing it from the ground there, though perhaps there'll be some air flights. Certainly it's a wonderful opportunity to see a total solar eclipse, especially if you can get to a site like Easter Island or out in one of the ships or in the air over Chile or anywhere else.

The two central solar eclipses, the annular eclipse of January 15th and the total eclipse of July 11th, 2010, will be succeeded by a year, 2011, when there are no central eclipses at all. There will be four partial eclipses in 2011 visible at various parts of the globe.

This is Jay Pasachoff, professor of astronomy at Williams College in Williamstown, Massachusetts, and chair of the International Astronomical Union's Working Group on Eclipses. We spend a lot of time and effort from the Working Group on Eclipses of the International Astronomical Union in educating the people in the various countries on how to watch the eclipse safely, what kind of eye protection they need for all times except when there is a total solar eclipse. The partial phases or an annular eclipse require eye protection or looking away from the eclipse in a projected image, either from a telescope or binoculars, or from even a simple pinhole camera, a hole punched in a piece of paper, projecting an image of the shape of the remainder of the sun onto a cardboard or onto a wall or even just under a tree from the interstices of the leaves onto the ground. So it will be interesting for all kinds of people to see these eclipses - partial, annular, and total.

End of podcast:

January 6th: Fighting the 2012 Hoax

kortney.hogan — Wed, 06 Jan 2010 11:00:19 +0000

Date: January 6, 2010

Title: Fighting the 2012 Hoax

Podcaster: Bill Hudson

Links: http://2012hoax.org
Music by Kevin MacLeod: http://www.incompetech.com/

Description: Bill Hudson from 2012hoax.org issues a call to action for all amateur astronomers, stargazers, and people just interested in space science. The 2012 doomsday hoax is gaining traction in a vulnerable population: school children.

Bio: Bill Hudson is an amateur astronomer in California. He has spent the last decade looking up, and is involved in astronomy outreach programs in the California central coast area. He is the publisher of 2012hoax.org, a wiki that seeks to document and debunk all of the doomsday rumors surrounding the year 2012.

Today's sponsor: This episode of "365 Days of Astronomy" is sponsored by no one. Please consider sponsoring an episode in 2010 for only $30.

Transcript:

This is Bill Hudson from 2012hoax.org. I’m very happy to be participating in the 2010 edition of the “365 days of astronomy” podcast. This is the first of 4 episodes that I’ve signed up for over the course of the year, and I hope to have some guests with me on future episodes. Today I’m going to be talking about a subject that is very important to me, and from the title of this episode, as well as the name of the website, you can probably guess that I’m going to talk about 2012. However, this is not a “2012 debunking “ episode, those will come later in the year. This is a call to arms, or a call to action.

If you are listening to this podcast, then you are interested in astronomy in some way. Many of you are amateur astronomers, like I am. You might be in a local astronomy club, or perhaps you are an occasional stargazer, or are just interested in astronomy in general without actually having astronomy as a hobby. Regardless of your level of participation, your interest in astronomy makes you uniquely qualified to debunk the “2012 doomsday” nonsense. So… I’m calling on you to help.

I became interested in the “2012 doomsday” nonsense because of my outreach into local schools, where I go into elementary school classrooms and give a talk on astronomy. I’ve been doing that for about 4 years. A couple of years ago I started getting a lot of questions from the kids about “the end of the world” and whether it was going to happen in 2012. I have spent a great deal of my free time in 2009 researching and debunking the various “2012 doomsday” rumors, and writing about them on 2012hoax.org. There are several people who are writing content for the site, and that is a big help, but I’m not here today to ask for more authors. What I am here to do today is to challenge you.

It is not enough to write about why the “2012 doomsday” is nonsense on a website. One website, or ten, or even a hundred, can’t compete with the vast sea of nonsense that is the “2012 phenomenon”. Sites like Yahoo!Answers and YouTube are full of people saying all kinds of crazy things about what will happen in 2012. There are thousands of videos on YouTube predicting various catastrophic events.

Even that is not as pervasive and persuasive as the shows that are playing on various cable and satellite channels. Channels such as the History Channel that once could be relied on to show quality programming have bowed to the pressure of ratings, and are now showing things like “Nostradamus 2012”, which is essentially an hour long brain-numbing mix of misleading statements, bad science, and outright falsehoods.

All of this has lead to what is perhaps the most persuasive vector of disinformation: Word of mouth. Consider that companies spend quite a bit of money in attempting to get a new movie or product to “go viral”, where people tell their friends about it. The marketing executives know that if your cousin tells you something, then you are more likely to listen than if a complete stranger tells you the same thing, and that if your parent or child or sibling tells you the same thing, you are more likely to listen than if it was your cousin.

This brings us to the most chilling aspect of this hoax: School kids. As much as this hoax has spread among adults, it is running like a wildfire through schools, especially at the upper elementary and junior high level, propelled by word of mouth. Kids are telling other kids that “the world is ending in 2012” and that the adults are keeping it secret. This appears to “sell” really well in the ten to eighteen year old age group, judging from the ages of people leaving comments at 2012hoax.org

So, what are we to do? Obviously, I’ve taken the approach of documenting and debunking, to the best of my ability, all of the 2012 rumors I can lay my eyes on. I hope that the website is useful as a resource, and that it serves to calm people’s fears, but this is not enough. Obviously the audience of the website is limited. Kids who may not have regular internet access are hearing about this from their classmates at school (remember, “Viral Marketing”) What is needed is a way to get the essential information, that the “2012 doomsday” is a hoax, directly to the kids to counteract the rumors.
This is where you come in.

As I said before, I became involved in this through my outreach into the local schools. This is where we can be most effective. I challenge you as amateur astronomers, as astronomy clubs, or as hobbyist stargazers to contact your local schools, libraries or other venues where you can reach a lot of kids, and talk them into letting you do a program on why “2012” is not real.

This is a perfect opportunity to teach these kids the differences between science and rumor. Use it to educate them about how science really works, and introduce the scientific method to them. Talk about things that we know are impossible (such as invisible planets on 3,600 year orbits), but also talk to them about what we know is real.
So, there you have it. This is my challenge to you. I’m throwing down the gauntlet. Get out of your comfort zone. Don’t just shake your head and wonder how this rumor, this hoax, this fraud got to be so widespread, but rather get out and do something about it.

If you think I am taking this way to seriously, then I invite you to read some of the comments in the forums at 2012hoax.org. What I am afraid of is that kids will become so distraught by this hoax that some of them will take their own lives.

So yes, I do take it seriously.

Do you?

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.

January 4th: Dark Days of Winter

kortney.hogan — Mon, 04 Jan 2010 11:00:12 +0000

Date: January 4, 2010

Title: Dark Days of Winter

Podcaster: Alice Enevoldsen

Organization: Pacific Science Center, Seattle, WA: pacificsciencecenter.org

Alice's AstroInfo: alicesastroinfo.com

Description: In today's podcast Alice answers a phone call from a friend, and they explore the dark days of the northern hemisphere's winter: the solstice, the day of the earliest sunset, the day of the latest sunrise, perihelion, and examine why these dates don't all coincide. She'll show you how to make an analemma, explain why you don't need to think of the equation of time as an equation, and guide you through a kinesthetic way to visualize the different short, dark, cold days of winter.

Bio: Alice Enevoldsen is currently the planetarium specialist at Pacific Science Center in Seattle, Washington, a part-time evening Astronomy instructor at South Seattle Community College, and volunteers as one of NASA's Solar System Ambassadors. She has been working in planetariums since 1996, has a B.A. in Astronomy-Geology from Whitman College, and a Masters in Teaching from Seattle University. Her fascination with the stars led her to try her hand at astronomy research, where she realized that her calling in life was actually to share her love of the stars and excitement about astronomy with as many people as possible.

Today's sponsor: This episode of "365 Days of Astronomy" is sponsored by no one. We still need sponsors for several days in 2010 -- please consider sponsoring a day! Contact us at signup@365daysofastronomy.org

Transcript:

Telephone ring.
Hello, this is Alice. Oh hey hi, I'm glad you called. Yeah, yeah you're right. Yesterday, January 3 was perihelion - the Earth's closest point to the Sun. Pretty cool that that happens in winter, isn't it? Yeah, I know, kinda mind-blowing.

Anyway the real reason I wanted you to call, I wanted to talk about the fact that January 3 was also the latest sunrise of the year. Yeah no, not December 21 the solstice, but January 3. Yeah, I always thought that the latest sunrise and the earliest sunset took place on the solstice because that's the shortest day therefore it should have the latest sunrise and the earliest sunset. That makes sense, right? But it's not true! The earliest sunset takes place weeks before the solstice, round about December 6th here in Seattle. That's the earliest sunset. And the latest sunrise isn't all the way until January 3.

So it's kinda weird about why this is. It has to do with this thing called the equation of time. Now, you can represent the equation of time as and equation, but you can also see a representation of it by looking at an analemma. So let me tell you a little bit about how you get an analemma.

Start with noon. Think about where the Sun is at noon. Point out the window, where is the Sun at noon? Now, I hope you're not pointing straight up because most people in the world don't actually get to see the Sun straight up over their heads at noon - ever, any time of the year. Now, there are some. Everybody who lives between the Tropics of Cancer and Capricorn gets to see it at least one day out of the year. But the rest of us, we don't get to see it. Generally it is going to be, if you're in the Northern Hemisphere, it will be directly above South. Some number of degrees above South will be the highest point that the Sun gets to. And if you live in the Southern Hemisphere it will be some number of degrees above North that you'll be able to see the Sun at noon.

Now, when it gets to that highest point in its path across the sky, that's called astronomical noon. That's the definition of astronomical noon. Next time you see it right there at its highest point look at your watch: probably isn't reading noon, because we have time zones and all kinds of things like that. But also, even more importantly, that's not the noon that really matters.

We've got two different kinds of time that we're dealing with. Apparent solar time, which is what I just told you about. It's noon when the Sun is at the highest point in the sky. You can read this with a sundial a little bit, you can also read it by measuring the angle of the Sun and making sure that it is exactly halfway across its path across the sky. So you've got apparent solar time, but you also have mean solar time. Now, mean solar time is what we really use in terms of determining the number of hours that have really passed. Mean solar time is if you took a clock, a perfect clock, and on the vernal equinox, March 21, you set that clock to noon the second you saw the Sun cross over the meridian - the second you saw the Sun get to its highest point - and then you let that clock run for a year, at the end of that year on the next vernal equinox, March 21, when that clock reads noon, the Sun will be right there exactly where it should be: at its highest point. Okay, so that's mean solar time. It means that we're averaging it out over a year.

Now the Sun, as we move around the Sun, it appears to move a little faster or a little slower through our sky because of the equation of time. Most of this is because of the eccentricity of the Earth's orbit around the Sun. We're not orbiting in a perfect circle. A little bit of it has to do with the tilt of the Earth, so it's really a pretty complicated little equation, but the effects are interesting and fun.

So, we have the equation of time affecting how fast the Sun is moving across the sky. (Yes, it's not the Sun moving, but effectively, from our point of view, while we're watching the Sun rise and set it looks to us like the Sun is moving.) So, effectively, as the Sun is moving across the sky, some days of the year it moves a little slower and some days it moves a little faster. So, when noon comes, some days it's behind where it should be. It's not yet at its highest point. And some days its in front of where it should be, not yet at its highest point or, oops, past being at its highest point actually.

Now, with your perfect watch, if you go out, you set up a camera, and you take a picture of the Sun every day at noon by your perfect watch, what you're going to see, when you put all those pictures together, is a figure-8 shape. That is the analemma, it is also a great representation of the equation of time. Okay, now if you don't want to spend a year waiting to see that picture, just Google "analemma" or you can stop by my website: www.alicesastroinfo.com, and I'll put up a picture for you. Also 365 Days of Astronomy will have a link up to my website from their website if that's easier for you.

So, how does the equation of time make the earliest sunset happen before the solstice and the latest sunrise happen after the solstice? Let's get back to that. It's because the entire day is shifting a little bit. And I keep wanting to say it's shifting left to right because I've laid out the hours on a number line, and that's how I'm visualizing this. So, why don't you visualize it with me? And I found it a little too complex to lay out the entire number line for a day, so I'm just using the numbers one through ten: they're representing hours. I'm pretending we have a ten-hour day. Instead of a 24-hour day, we've got a ten-hour day. We've just got a number line: one through ten. Also, you've got ten fingers, so if you're sitting on the bus, you can just hold your hands out in front of you and you've got that number line that you can look at.

Now, think about this: if we've got a solstice that's four "hours" long, it starts at "three" and it ends at "seven." So, the Sun rises at "three" and it sets at "seven". So noon is at "five" there. Okay? So we've got a pretty short solstice day there. Now, I'm not even going to go into minutes. I'm going to say everything changes by whole hours. The day after the solstice has to be a little bit longer. So instead of being four "hours" long, it is going to have to be at least five "hours" long. All right? And, let's go with the one that has the latest sunrise. So let's say the sunrise is just an hour later so instead of our solstice starting at "three" we have our day starting at "four" and then you've got to count a five "hour" day beyond that: six, seven, eight, nine - so the Sun sets at nine. So we've shifted our entire day to the right.

Let's do earliest sunset, okay? So the earliest sunset, to get our earliest sunset it's going to have to happen before "seven" so it will have to happen at "six" which means our sunrise is going to have to happen at "one." Now remember, these aren't real hours we're working with because we're just doing a ten-hour number line. I'm just showing you how the whole day is shifting left to right. But, from "one" to "six" is once again a five-hour "day" instead of that four-hour "day" that our solstice was. And our solstice does not have the latest sunrise or the earliest sunset like that. Now, in the real world we have to deal with a lot finer methods of measuring, and it turns out these sunsets are only off by a couple of minutes from each other.

And you can look this up. I get a lot of my information from the U.S. Naval Observatory. They have a couple of great resources: one is "Sun and Moon Data for One Day," they'll also give you an entire year's worth of sunrises and sunsets if you'd like, and so you can look at those. They also have a really great post called "The Dark Days of Winter" which is where I got a lot of the information for this so check that out. But in Seattle, that earliest sunset is 4:18pm. The sunset on the solstice was 4:20pm - so we're not talking about a big difference here.

Alright, well, we've talked about a lot of things today. Lot of vocabulary words, and I hope you go and look some of them up. If you have any more questions give me a call. I will talk to you later. Okay, yeah. Bye!

And in case you didn't catch that, my name is Alice Enevoldsen, I'm the planetarium specialist for Pacific Science Center in Seattle, Washington - pacificsciencecenter.org and the writer for Alice's AstroInfo alicesastroinfo.com.

End of podcast:

January 2nd: Water on the Moon

kortney.hogan — Sat, 02 Jan 2010 11:00:29 +0000

Date: January 2, 2010

Title: Water on the Moon

Podcaster: Nancy Atkinson

Links: Universe Today, Astrosphere New Media Association. LCROSS mission info, and links to download the song "Water On the Moon" by John Marmie

Description: 2009 was a "watershed" year for lunar exploration, as five different spacecraft were involved in discoveries of water on the Moon. Let's take a look back at the discoveries and look ahead to what explorations lie ahead.

Bio: Nancy Atkinson is the Senior Editor for Universe Today, and works with the Astronomy Cast podcast and 365 Days of Astronomy.

Today's sponsor: This episode of "365 Days of Astronomy" is not sponsored. Please consider sponsoring a podcast in 2010.

Transcript:

Music from "Water On The Moon"
Dr. Carle Pieters: Well, the Moon continues to surprise us. Widespread water has been detected on the surface of the Moon. You have to think outside the box on this. This is not what any of us expected a decade ago. But widespread water has been detected on the surface of the Moon.

Nancy Atkinson: That was Dr. Carle Pieters at a press conference on September 23, 2009 announcing that three different spacecraft had confirmed there is water on the Moon. But the news of water on the Moon didn't end there in 2009. Later on, two other spacecraft were involved in more scientific findings that has given us a whole new outlook on our closest companion in space. Hi, this is Nancy Atkinson from Universe Today. We're starting a whole new year for the 365 Days of Astronomy in 2010, but I'm taking this opportunity to look back at one of the biggest space news stories from 2009 – which actually ended up being two big news stories.

Let's start with the first one: In September, data from three spacecraft –indicated that water exists diffusely across the moon as hydroxyl or water molecules — or both — adhering to the surface in low concentrations. Additionally, there may be a water cycle in which the molecules are broken down and reformulated over a two week cycle, --the length of a lunar day. This finding did not constitute ice sheets underneath the lunar surface, but actually water directly on the Moon's surface. However, the amount of water in a given location on the Moon isn't much more than what is found in a desert here on Earth, perhaps a few teaspoons across an area about the size of a football field. But there's more water on the Moon than originally thought.

The spacecraft involved were the the Chandrayaan -1 lunar orbiter and its Moon Mineralogy Mapper instrument, or M cubed, which found evidence of hydroxyl- and water-bearing materials, then there was the re-purposed Deep Impact probe, on its way to rendezvous with another comet in 2010. In June of 2009, the spectrometer on board also showed strong evidence that water is ubiquitous over the surface of the moon. And then archived data was reanalyzed from the Cassini spacecraft that flew by the moon in 1999 on its way to Saturn, and that data as well agreed with the finding that water appears to be widespread across the lunar surface.

If the data was there before, how could we have missed this previously?

Robert Green, project instrument scientist for the M cubed instrument gives this response to that question:

Robert Green: It's quite fascinating that no one has found this before because Apollo was there for decades, we've had robotic missions, the Japanese were there and the Chinese were there and they didn't see it. We saw it because we went there with the right instrumentation. The Moon Mineralogy Mapper has an extended spectrometer footprint region that was sensitive to the variety of water we are finding.

And what about the Moon rocks returned from Apollo missions? How could we have missed seeing the water in those rock, which we actually have here on Earth to study? Robert Green again provides insight into what happened:

Robert Green: The Apollo astronauts many important samples which includes soils and rocks, and all those rocks and soils were brought into the command module which had a humid atmosphere which the astronauts were living. So the water in the atmosphere interacted with those rocks, and put a signature in those rocks, which is just like the signature that we are seeing, but by the time they came back to Earth we assumed that signature was due to terrestrial contamination; from being in the command module, on Earth and in the Pacific. So those rocks have those signatures but up until today we assumed it was all associated with contamination. But now we've measured this signature directly on the Moon, there's no question of contamination and so that's the difference between what we've discovered and the extraordinary work that was done in the age of Apollo.

Nancy Atkinson: And the process for how water can actually be on the moon's surface is a little complicated, so I'm going to let Robert Green explain it:

Robert Green: One of the hypotheses were are working with is that there is oxygen in the rocks on the surface of the Moon, there is hydrogen coming from the sun hitting those rocks. Oxygen and hydrogen together make water, so there could be a process with the solar wind carrying the hydrogen which makes water on the surface of the Moon.

Nancy Atkinson: Ok, now let's move on to the second part of our water on the Moon news from 2009. On October 9, , the LCROSS mission, or the Lunar CRater Observation and Sensing Satellite successfully crashed an impactor into a permantley shadowed crater near the moon's south pole. Even though the impact didn't create a plume that was much hoped for by those attempting to observer the impact from Earth, the science team from LCROSS announced on Nov. 13 that they had hit paydirt, or pay-regolith, perhaps. Here's Tony Colaprete, principal investigator for LCROSS:

Tony Colaprete: Indeed yes, we found water. We didn't find just a little bit, we found a significant amount. If you remember about a month ago we were talking about teaspoons into glasses from an area about the size of a football field, well now I can say today in the 20-30 meter created by LCROSS, we have maybe about a dozen of these two gallon buckets worth of water.

Nancy Atkinson: Colaprete said they also found signatures of other compounds as well in the impact site in Cabeus Crater, including sodium and carbon dioxide, which they are still analyzing.

There are potentially two types of water on the moon: exogenic, meaning water from outside sources, such as comets striking the moon's surface, and endogenic, meaning water that originates on the moon. The LCROSS team says that where the water in Cabeus crater came from is yet to be determined, whether it was delivered there by comets and meteorite hits or if some process within the Moon or on the surface is creating the water. The M cubed team, suspects that the water they're seeing on the moon's surface is endogenic, that it is coming from the process on the Moon itself that Robert Green talked about.

Mike Wargo, NASA's chief lunar scientist, said the cold traps in the permanently shadowed craters of the Moon are like the dusty attics or junk drawers of the solar system, and that they collect stuff from the solar system's evolution. And he added, We're only just begun to tap into our understanding of the Moon.
The other spacecraft that played a part in the LCROSS findings was the Lunar Reconnaisaince Orbiter, that newest lunar orbiter, which made observations of the crater and plume created by LCROSS.

Mike Wargo talked about how LCROSS and LRO will help our future explorations of the Moon:

Wargo: Well overall both of these missions have been highly successful, so far. The fact that LCross was able to confirm the presence of water in these permanently shadowed regions has significant scientific implications. It confirms prior theories and it gives us potential to have resources to us when we continue to explore beyond lower earth orbit.

The real beauty of both of these missions is that NASA is using the best it has to get the information it needs to continue to explore we knew that the scientific community was the place to go to get the experts and about how to make the measurements on the moon that we’ll need to explore safely and effectively as we go beyond lower earth orbit and LRO is delivering in spades."

Nancy Atkinson: As another member of the LCROSS team said, these new findings have really turned our understanding of lunar water on its head, and that we need to keep our minds open of what this is telling us. It's no longer Apollo's Moon, its our Moon.

As we look ahead to what new information we'll garner from our explorations of the Moon in 2010 and the years beyond, I'll leave you with a clip from a song called "Water on the Moon" written by LCROSS Deputy Project Manager John Marmie.

End of podcast:

December 29th: Decoding Iapetus: An Exercise in “Sybil” Engineering

kortney.hogan — Tue, 29 Dec 2009 11:00:32 +0000

Date: December 29, 2009

Title: Decoding Iapetus: An Exercise in "Sybil" Engineering

Podcaster: Kevin Grazier

Links: Cassini mission, CICLOPS Cassini image site.

Description: If planetary scientists could take the moons of Saturn and, knowing what we know, re-assign the names already given them, the moon Iapetus would certainly become Janus. Janus was a two-faced god from Roman mythology, and Iapetus is the most two-faced object in the Solar System.

Bio: Dr. Kevin Grazier is the Investigation Scientist and Science Planning Engineer for the Cassini/Huygens Mission to Saturn and Titan. He also performs large-scale computer simulations of Solar System dynamics, evolution, and chaos, and teaches classes in basic astronomy, planetology, cosmology, the search for extraterrestrial life, and the science of science fiction at UCLA and Santa Monica College.

Dr. Grazier also served as the science advisor for the Peabody-award-winning SyFy Channel series Battlestar Galactica, and currently serves that role on Eureka and the NBC animated series The Zula Patrol. He is also co-author of the upcoming book The Science of Battlestar Galactica.

Today's sponsor: This episode of "365 Days of Astronomy" is sponsored by Joseph Brimacombe, a mega-enthusiastic amateur astronomer based at the Coral Towers and Macedon Ranges Observatories in Australia, and the New Mexico Skies observatory in the United States and is dedicated to: James Cameron, whose movie "Avatar" took me to a world I'd imagined as a 10 year old boy peering through a 2 inch refractor; and as a 50 year old man peering through a 20 inch reflector. James, you are a global "life enhancer". Don't ever stop. We need you. Please google "Joseph Brimacombe, photostream" for further information.

Transcript:

This time of year, as the current NFL regular season winds down, a common feature of sports magazines and web sites is a hypothetical re-draft. In other words, if NFL teams could have known in advance how rookie players would perform in their first season last April before the draft, how differently might that draft have played out?

In a similar vein, if planetary scientists could take the moons of Saturn and, knowing what we know, re-assign the names already given them, the moon Iapetus would certainly become Janus. Janus was a two-faced god from Roman mythology, and Iapetus is the most two-faced object in the Solar System.

I’m Kevin Grazier, and welcome to the International Year of Astronomy podcast for December 29th, 2009.

Iapetus is the third largest moon of the Saturn system, and the 11th largest in the Solar System. It is one of the more distant moons of Saturn, orbiting at a distance 3,561,300 kilometers – that’s 2,213,000 miles or about 60 Saturn. Seen from Iapetus, gigantic Saturn appears about 4 times larger than the full moon seen from Earth. The density of Iapetus, of just under 1.1 g/cm3 implies it’s composed largely of water ice.

Iapetus was discovered in October 1671 by Giovanni Domenico Cassini, the astronomer for whom the current Cassini mission at Saturn is named. Cassini noted that he could observe Iapetus while it was on one side of Saturn, yet not the other. He concluded, correctly, that this moon must be tidally locked in synchronous rotation with Saturn. That means that, like our moon, the same face of Iapetus permanently faces Saturn. That also means that, as it orbits Saturn, Iapetus has a permanent leading, and permanent trailing, side.

Cassini further concluded that one side of Iapetus is much darker than the other, which was confirmed by subsequent observations using higher powered telescopes. Until recently, the explanation of the two-faced nature of Iapetus was the oldest unsolved mystery in planetary science.

2001 Mission

Science fiction author Arthur C. Clarke used this dichotomy in “2001: A Space Odyssey. In the movie version, a large black monolith of extraterrestrial origin is discovered on the moon. The monolith sends a powerful transmission towards Jupiter, and the spacecraft Discovery and her crew are dispatched to investigate, and they find an enormous monolith, sharing an orbit with the jovian moon Io. In the novelization, however, the monolith was situation on Saturn’s moon Iapetus. This explained Cassini’s observation back in the 17th century: as Iapetus circled Saturn in its 80 orbit, periodically the black monolith came into view.

Voyagers in 1981

As with Clarke’s spacecraft Discovery, NASA spacecraft have investigated this unusual moon as well. In 1981 the twin Voyager spacecraft sailed through the Saturn system. While Voyager 1 was able to view Iapetus only from a very great distance, on August 22 of that year Voyager 2 was able to image Iapetus from a distance of 909,000 km.

What Voyager 2 saw literally looked like a Yin/Yang. One side of Iapetus was nearly black, the other quite bright. We learned that Iapetus is the most “contrasty” body in the Solar System, yet we were not much nearer to answering “why”?

With a density that suggests Iapetus is composed largely of water ice, the nature of the light areas of this moon was no mystery. From where did the dark material come, however? Two hypotheses were suggested as the explanation, the endogenic model vs. the exogenic model. The endogenic model held that some process was forcing dark material from the interior of Iapetus to its surface. The exogenic model, on the other hand, suggested that there may be dark material in the orbit Iapetus that is being swept up by its permanent leading edge.

The hope was that NASA’s Cassini orbiter would shed some light on this long unsolved mystery after its arrival in July 2004.

Cassini Flybys

Iapetus is a distant moon of Saturn, and its orbit is inclined 15.5 degrees to Saturn’s ring plane. This explains why, during its four year nominal mission, Cassini trajectory took it near to Iapetus only twice.

On December 24th 2004 (Pacific Time), the Cassini spacecraft released the European Space Agency’s Huygens probe that had been riding piggyback since launch. It would be another 2 ½ weeks, until January 14 2005, before Huygens would plunge into the atmosphere of, and subsequently land upon, Saturn’s largest moon Titan.

Cassini actually lanched Huygens when both spacecraft were outbound from Saturn. Both spacecraft reached the most distant part of their orbit from Saturn, called perikron, before they plunged back towards Saturn and Titan.

As Cassini neared perikron, it took a brief break from the Huygens mission to observe Iapetus – it passed within 123,400 km of Iapetus, less than 1/7th the distance of Voyager 2. Initially the flyby distance was scheduled to be in the range of 65,000 km, but mission designers, unsure of the mass of Iapetus and its potential gravitational influence on the now-separate Cassini and Huygens probes, chose to give this moon a wider berth. The spacecraft, nevertheless, send back breathtaking images.

After the Voyager mission, scientists described the dark side of Iapetus as being “as dark as freshly laid asphalt”, and the light side “as bright as freshly-fallen snow.” The images sent back by the Cassini spacecraft have confirmed that the dark side is, indeed, very dark… but the light side is more like “Snow… in Detroit… in March.”

Apparent also at the light/dark boundary were streaks – where dark material looked almost windblown across the surface of Iapetus. Only Iapetus has no atmosphere. This seemed to argue in favor of the exogenic model for the source of dark material.

On 10 September 2007 Cassini flew even closer to Iapetus, and came within 1700 km. Careful analysis of the images from this flyby have revealed a third model for the source of Cassini’s dark material, and those results published in a recent issue of the journal Science.

Imagery shows that Iapetus is, indeed sweeping up reddish dust in its orbit around Saturn. Another process though, called thermal segregation, makes the bright areas brighter and the dark areas darker.

Since Iapetus orbits slowly around Saturn, its dark regions are exposed to the sun for long periods of time. The light areas are as well but the light areas, being light, reflect sunlight. The dark material absorbs sunlight and warms. This causes the nearby and underlying ice to evaporate, and it is eventually redeposited on the bright side.

This mystery, nearly 340 years old, seems to be on its way to being solved.

Walnut shape and mountain Ranges

Cassini imagery also revealed that the shape of Iapetus is similar to that of a walnut. The ratio of its polar diameter to its equatorial diameter suggest a body that was spinning very fast, a 17 hour rotation rate, when it formed – not spinning once every 80 days as it is now.

Cassini has also observed a HUGE range of 20 km high mountains that run along the equator of Iapetus. Some scientists have suggested that this is merely a result from when Iapetus spun much more rapidly, while others have suggested that Iapetus may once have had its own ring, that subsequently collapsed to its surface at the equator.

The light/dark nature of Iapetus may be well on its way to being solved, but there are new mysteries arising from this mysterious moon.

Upcoming flybys in XM and XXM.

There were no flybys of Iapetus, even distant ones, scheduled in Cassini’s Extended, or Equinox Mission. There are, however, two distant flybys slated in the trajectory currently proposed for Cassini’s Extended Extended, or Solstice, Mission. On Jun 7 2011 Cassini will pass within
863,000 km of Iapetus. It will pass within 979,000 km on Mar 30 2015. Although these are far more distant than the two flybys during Cassini’s nominal mission, given the spacecraft’s more advanced imaging systems, these should still provide imagery superior to that of Voyager 2. So, we may still learn something new from these encounters and, in the near-term, the book still isn’t closed on Iapetus.

You can learn more about Iapetus, Saturn, the Cassini and Huygens spacecraft, or follow the Cassini mission’s progress at saturn.jpl.nasa.gov. The Cassini Imaging Team site is at www.ciclops.org. Thank you for listening

End of podcast:

December 25th: Star of Wonder

kortney.hogan — Fri, 25 Dec 2009 11:00:44 +0000

Date: December 25, 2009

Title: Star of Wonder

Podcaster: Adler Planetarium

Organization: Adler Planetarium, Adler Night and Day podcasts

Description: Star of Wonder examines the theories behind the celestial event that prompted the Magi (Three Kings) to travel to Bethlehem. Was this light an exploding star, a brilliant comet, or an unusual grouping of planets?

Bio: The Adler Planetarium — America's First Planetarium — was founded in 1930 by Chicago business leader Max Adler. The museum is home to three full-size theaters, including the all-digital projection Definiti® Space Theater, the Sky Theater which utilizes a Zeiss optical projector, and the Universe 3D Theater. It is also home to one of the world's most important antique instrument collections. The Adler is a recognized leader in science education, with a focus on inspiring young people, particularly women and minorities, to pursue careers in science.

Today's sponsor: This episode of "365 Days of Astronomy" is sponsored by Craig Clark.

Transcript:

Mark
Welcome to a special edition of the Adler Planetarium's bi-weekly podcast, Adler Night and Day. The Adler Night and Day podcast provides listeners with a glimpse of what you can see in the night sky as well as updates on recent solar weather, and riveting conversation. For the 365 Day of Astronomy, daily podcast of the IYA, we'll be concentrating on the riveting conversation. Without further ado, I'm your host Mark and today I'm joined on Adler Night and Day by Dr. Marvin Bolt, curator and Vice President of Collections at the Adler Planetarium. Welcome Marv...

Marv
Hi Mark.

Mark
Today, we're going to examine the theories behind the celestial event that prompted the Magi, the three kings, to travel to Bethlehem, as depicted in the books of Matthew and Luke in the bible. So, Marv... astronomers, astrologers, historians, and hobbyists have dabbled in investigation of the star of Bethlehem story for nearly 2000 years. If anything, what is the historical context for the story?

Marv
Well, Mark, the only account that mentions the star of Bethlehem comes from the biblical text in Matthew's gospel, and that story informs and is shaped by the whole gospel, and it conveys significant messages to Jewish and Christian audiences of the first century. And I think it's really hard, if not impossible, to understand that story without understanding that context. So the story isn't just about science as we think of it today, that doesn't make it uninteresting, just a little bit different from what one might expect. Theology, science, and philosophy... they're all part of the same activity and, I would say, they are part of the same activity today but in very different ways from how it was 2000 years ago.

Mark
Sure. Okay, well so, was this light and exploding star? A brilliant comet? An unusual grouping of planets? Do we have any idea what the star of Bethlehem might have been?

Marv
I think we have some good ideas of about what it might have been and even better ideas of what it was not. I think if we want to understand what the star of Bethlehem was, we'll have to look at what a wise man, 2000 years ago would have thought was interesting and significant. And to do that, we're actually going to have to look at an event that is not just astronomical, but actually astrological, and if we're looking for something we think is significant we're going to miss the point. We have to look at something they would have thought was significant. So, people have come up with all sorts of suggestions. Was it a bright new star? Was it a comet? Was it something else that everybody else would have seen? Well, if we look at the story in Matthew it's pretty clear that King Herod and his cohorts, they had no idea what was going on. They hadn't noticed anything very bright or anything very unusual and that should tip us off that this star of Bethlehem was actually probably astrological and not astronomical. Now, what was the difference between astrological and astronomical? Well, he we have to look at what astrology was 2000 years ago and what people would have done was to look at events in the sky, such as, how the stars and planets and sun and moon were arranged and how they were positioned with respect to each other and how they would have tried to find meaning from those positions. About 2000 years ago an astronomer by the name of Ptolemy came up with a guidebook or a summary of astrology and by looking at that we can actually try to come up with a picture of how these wise men would've thought these kinds of events would've been significant, so... if you look at the internet and do a google search for star of Bethlehem bibliography, you'll find something that a friend and colleague of mine has put together with hundreds of references and I can say that virtually all of them, if not all of them, are wrong.

Mark
(Laughs)

Marv
Now how can I say they're all wrong? Well, if they're all different, at most one of them can be right.

Mark
Yah, there you go.

Marv
But most of them actually look at what we think is important, about ten years ago and astronomer at Rutgers University came up with a very, very different approach and he wrote up this book called “The Star of Bethlehem” and it's by Michael Molnar, and I would recommend that people take a look my friend's website and to take a look at this book for a really detailed description of what this event could be. But the basic idea of this is as follows: if you take a look at the guidelines of Ptolemy wrote 2000 years ago about how to interpret the heavens, you'll find out that certain planets have meaning if they're in positions relative to each other and these meanings indicate that a king is born Judea and it would point the way to Judea, although not to Bethlehem, it's not until the wise men consult the prophets that they are pointed to Bethlehem and actually find the way to the Christ child.

Mark
Okay, well, I'll be very honest, most versions of the star of Bethlehem planetarium show lead to as many contradictions as conclusions. For example, if you follow the logic of the Adler Planetarium's version, one of the possible conclusions would be that Zoroastrian astrology can accurately predict supernatural events, which is probably not an acceptable conclusion for Christians or astronomers. Do we go to far when we apply modern investigation techniques to religious and historical subjects?

Marv
I don't think it's inappropriate at all. But, I think we have to be really careful not to take the beliefs, opinions, and standards of 2000 years ago and apply them to today. Conversely, we also can't take the beliefs, opinions, and standards of today and apply them to 2000 years ago.

Mark
Right

Marv
So, if we take a look at the gospel story you notice some very interesting features that actually help you to understand what this event is about. There are some interesting parallels between Matthew 1 and Genesis 1 about a creation story and a creation story tells us, or gives us answers to, where did people come from? What's the origin of the universe? Were do people fit into the cosmos? And both Matthew and Genesis actually give some answers to this. And if you take a look at the gospel of Matthew, the story of the wise men takes place between two very different kinds of stories or events. The first is the people of God in the Old Testament and the people of God in the New Testament and this story actually makes a transition between a very small group of people associated with this people of God versus the whole, um, community of the world really, at the end of Matthew's gospel. And so, this marks that transition in an interesting way showing that this, um, this new Adam, this second Adam, the parallel of the first Adam is actually similar but quite different and opens up the world in a new way. So if we take a look at the story of the star of Bethlehem we actually see a lot of very interesting theological parallels and some interesting claims that this star of Bethlehem marks and signals.

Mark
Well, that brings up an interesting point. When you're dealing with a subject like this, do your religious beliefs have influence over your historical interpretation or vice-versa? Does your academic training influence your religious beliefs and how you might interpret this information?

Marv
I think that as an historian, my understanding of this event and this story is enhanced by religious beliefs and I think one's religious beliefs can be enhanced by historical beliefs, but they have to be held together very carefully because it's easy to have one bias and impact in ways that aren't very helpful. I think I'm a better historian because of my convictions about this story but I think my convictions are also strengthened by my own historical understanding as a scholar. So I don't think that they have to be held in contrast at all but they can mutually benefit each other and inform each other in helpful ways that make both of them much stronger.

Mark
Well, that's pretty insightful, thank you Marv and thank you for joining us on this special episode of Adler Night and Day.

Marv
Alright, thank you Mark.

Mark
I'd also like to thank the listeners of the 365 Days of Astronomy podcast. To listen to full episodes of Adler Night and Day please visit www.adlerplanetarium.org/podcasts.

End of podcast:

December 24th: Dancing in the Dark: Deities, Celebrations, and the Bottom of the Year

kortney.hogan — Thu, 24 Dec 2009 11:00:04 +0000

Date: December 24, 2009

Title: Dancing in the Dark: Deities, Celebrations, and the Bottom of the Year

Podcaster: Diane Duane

Link: http://www.dianeduane.com

Description: There’s something about the end of the year that makes people a little crazy… maybe because the Winter Solstice and the dark days surrounding it have presented human beings with numerous problems over the millennia that people have been building calendars and trying to run their lives by them. Will the days get longer again by themselves, or do we need to give the Sun a helping hand? Should this be our god’s birthday, or would Spring be better? Is this a bad time to end the year, or a good one? And when it does end… where’s the party?

Bio: Diane Duane is a native New Yorker living in Ireland, and a descendant of the first Mayor of New York City. She’s been writing science fiction and fantasy novels, TV, computer games, comics and whatnot for twenty-five years, in her own universes and others; in that time she’s written for characters as disparate as Batman, Sigurd the Volsung, Jean-Luc Picard, and Scooby-Doo. A lifelong love of astronomy has affected all her work, especially her “Young Wizards” young-adult fantasy series. She’s happy to live in a place where even a nearsighted person can see the Milky Way with the naked eye.

Today's sponsor: This episode of "365 Days of Astronomy" is sponsored by the National Radio Astronomy Observatory, celebrating Five Decades of Training Young Scientists through summer programs. Explore the hidden universe in radio at www.nrao.edu.

Transcript:

Hi there. My name is Diane Duane: I’m a science fiction and fantasy writer, and I live in Ireland.

Out here in the country there’s a line you start hearing from the neighbors around the middle of November when you meet them in the village or at the pub: “Sure the nights are really drawing in now, aren’t they?” At our latitude, around 55 north, the shortening of the daylight hours as the Winter Solstice approaches can be surprisingly oppressive. At the Solstice the Sun won’t rise until twenty to nine in the morning, and sets again by a little after four.

The annoyance of the long dark nights and short chilly days is offset by the knowledge that after the Solstice, the days will start getting longer. A constant flow of images sent back from satellites and people living in space have imprinted on the vast majority of human beings the reality of the situation: the Earth is round, it goes around the Sun once every three hundred sixty-five days or so, and it has a tilt to its axis that creates the seasons of summer and winter. Everybody knows that it would take cosmic events of more than mega-disaster-movie proportions to disrupt that ancient rhythm.

But Ireland, like many other countries across the world, is home to various ancient structures like the famous Newgrange passage tomb – carefully constructed and engineered five thousand years ago to analyze the Sun’s movements and predict its expected positions far into the future. These beautifully designed and fabulously expensive scientific instruments, which modern archaeoastronomy is now helping us understand, are a reminder that our distant ancestors didn’t share our certainty that after winter there’d be another spring.

These weren’t stupid people by any means. But the early sparks of civilization were scattered far apart, and lacking the ease of communication and information sharing that we’ve taken for granted for centuries, they just didn’t have enough data to be sure. Being far more intimately connected to the land than most of us are now, those most ancient peoples were very clear that if the Sun didn’t return after the winter, all human life would end. So each early culture took its own precautions, both scientific and religious, to make sure that the world kept working as it should. They were determined to make sure they knew where the Sun ought to be at the Equinoxes and Solstices, especially the crucial Winter one. And the religious texts of the earliest writing civilizations make plain their determination that if the Sun needed mankind’s help at that dangerous time, it would get it.

Around the world one can still find a scattering of the very oldest traditions along these lines: ceremonies in which fires were kindled and kept burning all through the longest night to scare away the nameless things that lived in the darkness, and show the Sun the way back. People danced around those fires in the dark, shouting encouragement to the day’s fire from the night’s ones, often leaping over the flames for luck– theirs, or the Sun’s. Their sympathetic magic-based methods might have been primitive, but their sentiments were no less heartfelt for that.

Later, as the first civilizations grew more stable and complex, so did the rituals and traditions. People planet-wide started personifying the Sun into a god or goddess so that it would be easier to work with, and hymns and ceremonies were constructed to help the Sun Gods return – some of them inspiring works of art like the Egyptian Pharaoh Akhenaten’s “Hymn to the Sun”. Later still, as expanding cultures bumped into each other and started exchanging knowledge, the accumulating data started suggesting that the Sun could be depended upon to keep coming back. This was almost certainly a huge relief to everybody. But the ancient cultural mainstreams don’t seem to have been relieved enough to stop the ancient ceremonies their ancestors had performed since time immemorial to help the Sun return. After all, some of them might have reasoned, you couldn’t be sure that the ceremonies hadn’t helped. At this late date, why rock the boat?...

With this basic conservatism in play, maybe it shouldn’t surprise us that so many remnants of those old celebrations and commemorations are still with us, though in forms sometimes so worn down by the flow of Time as to be almost unrecognizable. Here and there a glimpse of the old year-end fear and joy shines through the shadows of the past, like a Christmas tree ornament buried way in by the trunk; and the science of astronomy is the hook that holds the ornament on the tree.

Probably the first use of practical astronomy was in giving local farmers a straightforward count of days and a set of clear seasonal signposts to help them know when to sow and when to reap, when to put the cattle out and when to bring them in. For that you need detailed astronomical observations to plot the agricultural data against: and then, so that the people who need the information can get their hands on it, you need a physical calendar that can be written on parchment or papyrus or graven on stone, and ideally carried in your head.

It sounds simple enough. But even today a calendar isn’t something you just throw together on a couple of quiet afternoons… and additionally, calendar making in ancient days wasn’t strictly a scientific business. Often it was the religious authorities who commissioned the calendars. Behind their desire to be sure about when to plant the barley, there was also concern about knowing exactly when to enact rituals to give the local Sun God a helping hand and make sure the seasons stayed in the groove. Where the crucial and dangerous Winter Solstice was involved, the tension between the religious and the scientific impulses occasionally shows through… even when cultures developed calendars that were primarily lunar. Hanukkah, for example, is tied to the new moon closest to the Solstice – theoretically the winter’s darkest night -- in exactly the same way that Easter and Passover are tied to the full moon closest to the Spring Equinox.

Another effect the Solstice had was to affect the placement of some religious holidays in newly designed calendars. That dark bottom of the year in some cultures was considered so dangerous that the calendar-makers designated the four or five days on each side of the shortest day as “unlucky days” when contracts should not be signed or marriages celebrated. Often the New Year would be set for a month or so after the Solstice, when people felt the dangerous time was safely past. This was the case in Ireland, where the “old New Year” and the first day of Spring fall on February 2nd, the old feast of Imbolc – presided over by the Celtic virgin goddess Brigid of the Flames, mistress of fire, the Sun, and the sciences.

Now, the Winter Solstice can still have strange indirect effects on even modern religious holidays and the calendar dates on which they fall. For example, another reason that Brigid’s early February festival is the first day of the ancient Celtic year is that it marks the beginning of the lambing season. This has immediate resonances with Christian tradition, as the Gospel of Saint Luke states that the angels’ announcement of the birth of the Christ Child happened while the shepherds were spending the night out with their flocks. The only time shepherds bother to do this is when the sheep are lambing, and not even in a Mediterranean climate do sheep lamb in December. So what’s Christmas doing in December?

As it happens, the ancient Rome-based Church wanted to promote the Christmas holiday by associating it with an older one, ideally one around the Solstice, which in many ancient traditions was a time when gods of the Light celebrated their birthdays. The obvious candidate in the first century after Christ’s birth was the great Roman midwinter feast, the Saturnalia, which honored Saturn, the scythe-bearing god of age and time, and also of sowers and reapers and the ending year. This holiday, so popular with the Romans that over time it grew from one day to seven, handled the unlucky days on either side of the Solstice in typically pragmatic Roman fashion: by closing down the country’s businesses and holding an empire-wide party until it was safe to open up shop again.

During Saturnalia, government offices and law courts were closed, business clothes were dumped for the week, and even wars were put on hold. In memory of a long-past “golden age” of peace and equality over which Saturn and the older gods were said to have presided, slaves were given the week off and were waited on at meals by their masters and mistresses. Friends exchanged gifts of money and food, candles were lit to celebrate the returning light, and houses were decorated with evergreen boughs to suggest that life would once again inevitably follow the light’s return. There was also a lot of visiting back and forth and a ton of partying and feasting until the holiday was done.

Over subsequent decades the early Church seems to have had second thoughts about connecting Christmas with this holiday, as the Saturnalia started becoming increasingly secularized, with ever more emphasis on the boozy feasting and partying and upending of the status quo. Eventually the Emperor Constantine, having decreed the Sun’s day as an official day of rest, felt it more appropriate to attach Christmas to December 25th – the date to which the Solstice had been relocated in Julius Caesar’s reformed calendar -- and the birthday of the sun god Sol Invictus: the Unconquered Sun, eternally victorious over the winter dark. Despite continuing discussions about why it’s there, there Christmas has stayed, even through the calendar reforms that followed. (And it’s worth considering that without the Western calendar’s last few reforms, Christmas would now be falling sometime in May. It really doesn’t pay to get careless with calendars.)

Calendar management has come a long way since in its relationship with the great turning-points of the year. Nowadays we’re a lot more interested in whether we have to add a leap second on New Year’s Eve than in whether the Sun will rise again on December 22nd. Yet we can still reach back to touch the ancestors for whom that concern was vital. On Solstice dawns when the Sun defies all modern Irish expectations by actually being visible, you can stand inside the great Newgrange passage tomb and see the first sunlight shine down the hidden inner passage – by webcam. And as for less techie ways to do it, if you’ve turned on the Christmas tree lights this year, or lit a candle on the menorah, or eaten dumplings at Dong Zhi, or sat around the korsi at Shab e-Yalda and feasted with your family, then you’ve already engaged with the same energies as our most distant ancestors when they designed the first calendars and danced in the dark during the Solstice. Even with the Sun’s return a given, we can empathize with our foremothers’ and forefathers’ relief that the light was coming back, and that the world would keep on working for yet another year. And perhaps the cold dark Solstice time is a good one to consider that, though there’s always room for improvement, humans then and humans now are very much alike in all the ways that matter. Our connection to our ancient ancestors is the realization that though light itself is naturally of great value, it can mean far more than merely what it is.

In that spirit, to all of you who’re celebrating a dark-of-the-year holiday right now, I wish you peace, joy, and a continuing appreciation of the return of the Light.

For a collection of URLs to follow for more information about calendars and the Solstice, please go to this web address:

http://www.dianeduane.com/solstice

End of podcast:

December 19th: Lurking ULIRGS

kortney.hogan — Sat, 19 Dec 2009 11:00:08 +0000

Date: December 19, 2009

Title: Lurking ULIRGS

Podcaster: Sue Ann Heatherly

Organization: NRAO -- National Radio Astronomy Observatory

Description: While ULIRGs (You-lurgs) lurk in our local universe they are much more prevalent in the early universe! What’s a ULIRG, you ask? Join us as NRAO astronomer David Frayer describes his research characterizing these objects and what they tell us about galaxy evolution.

Bio: Sue Ann Heatherly is the Education Officer at the NRAO Green Bank WV site. She comes to astronomy by way of biology (BA in 1981), and science education (MA in 1985) She visited the Observatory as a teacher in 1987 and knew she'd found Camelot. She has been employed with the NRAO since 1989.

Today's sponsor: This episode of "365 Days of Astronomy" is sponsored by Astronomy Cast

Transcript:

SUE ANN HEATHERLY: Welcome to this addition of 365 Days of Astronomy podcasts. My name is Sue Ann Heatherly. I’ll be your host today, and this is our last podcast for the International Year of Astronomy, and we’ve enjoyed being with you.

For our December podcast, I’m joined by David Frayer, who is a newly. . .a new astronomer to NRAO. He’s been an astronomer for awhile, but he joined the staff at the Green Bank facility a few months ago. And welcome to the show. We’re happy to have you on our last podcast.

DAVID FRAYER: Happy to be here. Well, thank you.

SUE ANN HEATHERLY: All right, David. So, we’re going to talk about your research today, and, uh, we’re going to talk about this class of objects that you call ULIRGS. And, of course, I’m first going to ask you to, uh, to tell us what a ULIRG is.

DAVID FRAYER: ULIRGS are ultra luminous infrared galaxies, or they’re the most extreme examples of what we call just LRGS, which are Luminous Infrared Galaxies. They were discovered in the 1980s by the IRAS Satellite, and they’re relatively rare in the local universe. And you— They tend to show up and be the result of merging galaxies or interacting galaxies. So, if you look at our spiral galaxy, and you look at it’s infra. . .infrared, amount of infrared light that’s coming out and compare it to the stellar light that comes out, well, it’s a normal galaxy — it has a normal ratio. Uh, the infrared galaxies are infrared bright. They have more infrared light for the amount of— If you just looked at an optical picture and said “How bright is this object?” and you, you wouldn’t expect to see as much infrared emission. So, there is enhanced, um, emission coming out of the infrared.

SUE ANN HEATHERLY: So, if you were to use a regular optical telescope and look at these galaxies, uh, what would you see? Would they look like spiral galaxies? What, what do they look like?
DAVID FRAYER: Well, the lower luminosity ones you’d, you’d see maybe two spiral galaxies sort of close to each other. Um, the most luminous, the ultra luminous, or the ULIRGS, as we call them, you would, they were, they’re almost completely interacting galaxies. So, they would look like a train wreck. If the galaxies had a lot of gas to begin with, they would be infrared luminous. So, that’s the key; it’s not just fact that they’re interacting galaxies, but it’s inter, interaction between gas-rich galaxies, because then you have the gas and dust, or star formation. The star formation is heating up that dust and it’s re-radiating in the infrared, and it happens in obscured regions, meaning, you don’t, if you look at it optically, you don’t see where all the luminosity is coming out of.
SUE ANN HEATHERLY: Yeh, it’s going to—
DAVID FRAYER: It’s hidden by dust.
SUE ANN HEATHERLY: I wanted to ask you that. So, in some cases, these galaxies in the visible part of the spectrum just look like two isolated galaxies that happen to be close together.
DAVID FRAYER: They—
SUE ANN HEATHERLY: And you don’t see yet visibly the evidence for star formation. You don’t see extra star light.
DAVID FRAYER: You can see. . .they could be a little brighter, but if you look at the ratios, they would still. . .it would be under, they would be over luminous or extra emission in the infrared of what you see in the optical.
SUE ANN HEATHERLY: So, how, uh, common is it for galaxies to smash into other galaxies?
DAVID FRAYER: They’re rare locally, but a higher redshift, this is happening a lot more often. People in terms of just studying galaxy evolution in general are interested in studying this, this class of objects at higher redshifts.
SUE ANN HEATHERLY: So, you mean that as you look farther and farther, deeper into the universe—
DAVID FRAYER: It’s a thou—
SUE ANN HEATHERLY: —you see more examples?
DAVID FRAYER: Yeah, it’s a thousand times more common at a redshift of two than it is locally.
SUE ANN HEATHERLY: You’re an astronomer. What’s the. . .what’s your hypothesis as to why that’s the case?
DAVID FRAYER: Well, first of all galaxies had more gas in the past. And galaxies were closer together.
SUE ANN HEATHERLY: The universe was smaller, I guess.
DAVID FRAYER: The universe was smaller.
SUE ANN HEATHERLY: Yeah.
DAVID FRAYER: So, you had a lot more interactions.
SUE ANN HEATHERLY: Are these typically spiral galaxies that you see doing this?
DAVID FRAYER: Locally, what. . .yes, because, to get the, well, this is to get the extreme cases. There is a full spectrum. So, I mean, it’s sort of arbitrary where we draw the classification lines. So, we— The ULIRG is more than ten to the twelfth times a solar luminosity, but that’s just arbitrary. Uh, but, for those high luminosities, yes, it’s basically mergers between gas-rich systems, and the galaxies that are gas rich in the local universe are just spiral galaxies.
SUE ANN HEATHERLY: Uh-huh.
DAVID FRAYER: The mergers between elliptical galaxies without any gas, they would just go through each other — the stars wouldn’t care. You wouldn’t even. . .they wouldn’t really notice. I mean, they’re, the galaxies’ orbits could change if you’re looking at it from an outside reference frame, but you wouldn’t necess. . .you wouldn’t see a big burst of new star formation, because those galaxies have already consumed their gas. So, when you have merging galaxies that are gas rich, the gas sort of runs into each other, falls into the middle of the potential well, and then there is nowhere for it to go, and then, boom, you get a lot of star formation, as well as you get AGN activity, as well.
SUE ANN HEATHERLY: What, what’s an AGN?
DAVID FRAYER: Oh. Sorry. It’s a black hole that’s active; meaning, gas is falling in on it, so then it’s bright.
SUE ANN HEATHERLY: In your research, uh. . .uh, you’re part of this wave of renewed interest. . .
DAVID FRAYER: Yeah.
SUE ANN HEATHERLY: . . .in these.
DAVID FRAYER: Well, I was interested even before. So, the initial extreme examples that were found at high redshift, I was involved in studying their gas properties by searching for molecular gas using CO as a tracer.
SUE ANN HEATHERLY: Good. I’m glad you brought that up, because, we have been talking about galaxies that are bright in the infrared, but here you are at a radio astronomy observatory, rather than an infrared observatory, although you’ve—
DAVID FRAYER: Yeah.
SUE ANN HEATHERLY: —worked with infrared telescopes too.
DAVID FRAYER: That’s right.
SUE ANN HEATHERLY: So—
SUE ANN HEATHERLY: Tell us—the radio connection.
DAVID FRAYER: Well, the ra. . .it. . .for me personally, it’s going full, full circle. I started in radio, in millimeter wavelengths, looking for CO emission from whatever we could see at high redshift. And the, and the things that you could see in CO are the most luminous cases, which happen to be these ultra-luminous or even hyper-luminous, another order of magnitude, more luminous than . .than ultra-luminous is hyper-luminous galaxies. And they were uncovered by the SCUBA instrument on the JCMT. So, when
SUE ANN HEATHERLY: Which is the. . .?
DAVID FRAYER: Oh, it’s a, uh. . . submillimeter instrument that is studying dust continuum.
SUE ANN HEATHERLY: And that’s the James Clerk Maxwell Telescope.
SUE ANN HEATHERLY: I also want to define for everybody, just in case when we’re talking about “CO”, we’re talking about carbon monoxide. . .molecules.
DAVID FRAYER: That’s right.
SUE ANN HEATHERLY: Existing in these galaxies.
DAVID FRAYER: But it happens to be one of the most common molecules that you can see.
SUE ANN HEATHERLY: Okay. So, you started out looking for carbon monoxide at high redshifts, which means that the, the spectral lines from the carbon monoxide would be at low enough frequency--
DAVID FRAYER: Frequency. That we could—
SUE ANN HEATHERLY: —to see them.
DAVID FRAYER: We could see them.
SUE ANN HEATHERLY: Okay.
DAVID FRAYER: And then, they had to be bright enough so we could detect them, because our instrumentation was pretty poor back then. So, we did all the easy ones that we could see, because our instrumentation was somewhat limited. And then, after, it sort of hit a stopping point, and then I moved more towards doing infrared work, because then, then I joined the Spitzer Space Telescope, which does infrared research.
SUE ANN HEATHERLY: So, what are the questions that you’re trying to answer. . .answer now?
DAVID FRAYER: Now, I’ve mentioned the fact you have merging galaxies — so one of the hot topics is what fraction of the amount of stars that we see today come from one of these events versus more what we call quiescence, or, you know, more common star formation just percolating in the disks. And then, just understanding the evolution of different types of galaxies at high redshift and what they evolve into with low redshift.
SUE ANN HEATHERLY: So, is there any evidence that the Milky Way has merged, or—
DAVID FRAYER: Not. . .probably not a super major merger, because the common paradigm is that you, once you have two big spiral galaxies merging, if it’s sort of equal masses, they form something that’s more elliptical like and most of the gas is consumed. But certainly little dwarf galaxies and stuff have come through, and that has, uh, enhanced the star formation in episodes in the past, and there is evidence for that.
SUE ANN HEATHERLY: So, at some point in the future, we’re always told that we’re going to run into Andromeda or—
DAVID FRAYER: Yeah.
SUE ANN HEATHERLY: Andromeda, the Andromeda Galaxy will run into us. And what should we expect to see, if we’re around to see something—
DAVID FRAYER: That would be—
SUE ANN HEATHERLY: —during that merger?
DAVID FRAYER: That would be a very intense ultra luminous infrared galaxy phase, so. . .if we’re in the middle of our galaxy, where the action was happening, then I would guess a lot of the sky would be pretty bright, day and night.
SUE ANN HEATHERLY: Oh!
DAVID FRAYER: Potentially.
SUE ANN HEATHERLY: Yeah.
DAVID FRAYER: We’re out farther away, so what you would see would be just. . .you would see a big fuzzy thing in the sky. It’s something pretty bright. I would, I would guess something. . .you know, you would be able to, I would guess, a naked eye.
SUE ANN HEATHERLY: What do you hope to do with the, uh, with the telescope here?
DAVID FRAYER: But that’s not going to happen for—
SUE ANN HEATHERLY: I know. That’s— We don’t have to worry about it. I just always wonder how would our skies change.
DAVID FRAYER: --billions, a billion years or something. And the sun will survive just happily, probably. It will just keep on going around. It might not be going around the center of our galaxy, it will be going around the center of the two dynamic centers of the galaxies that merge together.
So, going-- You are getting ready-- You were-- You were asking me, before I jumped in there again, on how, what I’m doing now. So, I’ve done the infrared, so I’m going back and, uh, we’re now at a radio observatory, and Herschel and Spitzer, the infrared telescopes, we found tons of these high redshift objects. So, now we get to follow them up in radio wavelengths, HI observations for the neutral gas, CO observations for molecular gas. There is other tracers to study the dense molecular gas. So, radio astronomy should have a, an active area of research in the next ten years doing more traditional, what I call traditional studies, evolution of galaxies, not from their stellar light or optical emission, but from the radio emission studying the ISM, the gas and dust from which the stars form.
SUE ANN HEATHERLY: Well, that sounds like fun.
DAVID FRAYER: It will be.
SUE ANN HEATHERLY: Yeah. Well, uh, thank you so much for joining us today. And thank you all out there for tuning into 365 Days of Astronomy. I’m Sue Ann Heatherly and I’m here today with David Frayer.
DAVID FRAYER: Nice talking to you.
SUE ANN HEATHERLY: Okay!

End of podcast: