Date: July 19, 2010
Title: Where Do We Come From?
Podcaster: Carolyn Collins Petersen
Organization: Loch Ness Productions
Music from A Gentle Rain of Starlight, by Geodesium. (http://www.geodesium.com)
Description: Carolyn Collins Petersen, TheSpacewriter, muses on our cosmic origins, starting with our home here on Earth. It’s a story that takes you out to the most distant reaches of the universe.
Bio: Carolyn Collins Petersen is a science writer and show producer, as well as vice-president of Loch Ness Productions, (http://www.lochnessproductions.com/index2.html) a company that creates astronomy documentaries and other materials. She works with planetariums, science centers, and observatories on products that explain astronomy and space science to the public. Her most recent projects range from documentary scripts, exhibits for NASA/JPL, the Griffith Observatory and the California Academy of Sciences, to video podcasts for MIT’s Haystack Observatory and podcasts for the Astronomical society of the Pacific’s “Astronomy Behind the Headlines” project.
Today’s sponsor: This episode of “365 Days of Astronomy” is sponsored by the Physics Department at Eastern Illinois University: “Caring faculty guiding students through teaching and research” at www.eiu.edu/~physics/.
Transcript:
Where are YOU From?
Hi, I’m Carolyn Collins Petersen, TheSpacewriter.
What do you tell people when they ask you, “where are you from?” Most of us immediately think of our home towns… the places where we grew up. That’s great, at one level. But, trace your path back far enough, and you find out that you’re really from a much larger place – the cosmos.
The first step on the ladder of your cosmic lineage is your hometown. But, where’s that hometown located? Which continent?
Did you know that at one point in the past eons of Earth’s history, all the continents we know today were tied up in one huge supercontinent called Pangaea? The precursors of life we know today existed on Pangaea. And, there is strong evidence for several other supercontinents that predated Pangaea. However, in some sense, you COULD say that you came from Pangaea.
But, there’s more to your lineage than that. This succession of continents formed on Earth, the only planet that we know about (so far) on which life has formed and evolved. You’re part of the long evolutionary tree of life that populates this planet. So, you can also correctly say that you come from Earth.
Well, that’s all fine and good, but Earth had to come from somewhere before you could come along. By now, most of us know the standard formation scenarios for our planet – they boil down to this: The Sun and planets formed in a cloud of gas and dust some 4.5 billion years ago. Some of that material existed as cold hydrogen clouds, probably since the birth of the galaxy. The rest of the planet- and Sun-forming material came from other stars. Yes, that’s right, the stuff that formed Earth – and by extension – that formed you and me – came from the hearts of other stars as they aged and died. Some stars died quietly, blowing their stuff out to space while others vented their stuff out in supernova explosions. So, you could say that you’re from the stars. And, in a very literal sense, you’d be right.
But, there’s more to the story. The stars themselves have been and continue to be part of a huge starry metropolis called the Milky Way Galax y. It is nearly as old as the universe. Over time, smaller dwarf galaxies meshed their stars together as the Milky Way grew, in a process that repeated itself many times. Within the Milky Way, there are many, many sites of star formation — those clouds of gas and dust that coalesced to form stars, planets – and maybe on some of those planets – life.
So, you could also rightfully say that you are from the Milky Way Galaxy – that you are, in fact, a citizen of the galaxy. I like the way that sounds – “citizen of the galaxy.” It makes us seem cosmic and cosmopolitan — like we’re born to wander the interstellar realms, exploring the galaxy.
Well, we’re not just citizens of one galaxy. The Milky Way is part of a cluster of galaxies called the Local Group. It’s a gathering of more than 30 galaxies that travel the spaceways along with the Milky Way. Included in the group are the famous companions to the Milky Way — Large and Small Magellanic Clouds. There’s also the Andromeda Galaxy, the Triangulum Galaxy, and many others that are smaller and somewhat different from the Milky Way and Andromeda spiral systems. But, we live on Earth, which is part of the Milky Way Galaxy, which is part of the Local Group. So, we’d also be correct if we told everyone that we were from the Local Group. It’s a bit like the difference between telling someone you’re from Poughkeepsie, or that you’re from New York, or you’re from the United States, or boasting that you’re from Earth. It’s a matter of which scale you choose.
The Local Group is just one cluster of galaxies that make up the Virgo Supercluster, which is an even larger group of galaxies and galaxy groupings. So, you could also boast that you’re a Virgo Superclusterian, if you liked. And you’d be correct, but you also wouldn’t be at the end of your lineage. There’s an even bigger step – and that’s to realize that the supercluster is just one of many countless superclusters that comprise all the galaxies in the cosmos. So, your status as a citizen of the superclusters also includes the ultimate membership – citizen of the universe.
Your lineage as a life form on a small planet tucked away in a part of a spiral galaxy that’s just one of countless galaxies in the cosmos began when the cosmos was born – in the Big Bang, some 13.7 billion years ago.
All the hydrogen in the universe was created during the Big Bang. And – I’m making a big leap here from the Big Bang to you, but bear with me — hydrogen is a big part of our bodies. It’s the major component of water and WE are mostly water. The other elements found in our bodies – the calcium in our bones, the iron in our blood, the carbon molecules that are the underpinnings of proteins and amino acids – all those were cooked up inside populations of stars within our galaxy. And, they were all born, lived and died since the universe itself was born. Our lineage is directly traced back to the Big Bang, and so you could say that you’re from the Big Bang… although that might raise a few eyebrows. But, you’d be right.
So, the next time somebody asks you “where ya from?” you could answer with your hometown…or, you could proudly state that YOU are from the cosmos.
It reminds me of Max Erhmann’s famous poem called “Desiderata”, where he says, you are a child of the universe, no less than the trees and the stars. You have a right to be here. And, whether or not it is clear to you, no doubt the universe is unfolding as it should.”
If you’d like to read more about your cosmic lineage, surf on over to
www.thespacewriter.com/wp and click on the 365 Days of Astronomy page. And, thanks for listening, fellow cosmic citizens!
End of podcast:
365 Days of Astronomy
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