June 29, 2008 at 15:06 pm | Leave a Comment
Look Over Here…
It may come as a surprise to folks to learn that we on Earth don’t live in the middle of the Milky Way Galaxy. We actually live out in the suburbs, about 26,000 light-years away from all the action at the center of our stellar city. That’s actually a good thing, because from all accounts, the core of the Milky Way has a black hole or two, and a whole lot of starburst activity and other stuff going on, some of it not very healthy to be around. Those aren’t conditions conducive to a nice quiet life on a water-bearing world such as ours.
Nonetheless, like urban folk all over the world, sometimes we get an itch to see the “downtown” area with its bright lights and excitement. So, we try to look at the center of the galaxy, only to find that it’s hidden by dust clouds. In northern hemisphere summer, you can go out a couple of hours or so after sunset and look south toward the constellation Sagittarius (shown in the image above from Wikipedia). Just off the tip of the spout in the teapot shape of Sagittarius is where the center of the Milky Way is located. The bright clouds are stars that lie between us and the core of the galaxy, which is hidden behind dust clouds. For folks in the southern hemisphere, Sagittarius is going to be overhead or even north of overhead (depending on where you are). But, no matter where you live, if you can get outside and take a gander at Sagittarius, you’ll be looking toward the heart of our home galaxy.
Now, it turns out we can look through that dust if we use a telescope equipped with infrared detectors. Infrared light CAN get through the dust. The image at left is from the Spitzer Space Telescope, and it shows the core of the galaxy-the stuff we can’t see with our visible-light eyes. There are hundreds of millions of stars packed into that scene, along with dark dust clouds that even infrared light couldn’t pierce.
It’s kind of fascinating to go out and look up at that region of the sky, which seems rather placid in visible light. Yet, behind all those dust clouds are some fascinating events taking place. Think about it when you go out to check out the center of our galaxy when you’re stargazing over the next couple of months.
June 27, 2008 at 16:52 pm | 1 Comment
Complex Molecules in Space
A few months ago I attended a day-long workshop about the chemical origins of life. The talks were aimed at tracing the chemicals that make up our very basic units (RNA, DNA) from first principles to the garden of biologic diversity we inhabit today. One of the talks focused on the finding the chemical precursors of life in interstellar dust clouds, which is really kind of a mind-blowing concept. But, when you think about it, since everything is chemical in origin, it makes sense that some of the chemicals that existed in the cloud our solar system formed in would also play a part in the origin of life.
There are organic molecules everywhere in space (and obviously here on Earth, but also at Jupiter, Saturn, and Titan. Researchers at Imperial College in London (England) have identified xantine and uracil — two very complex molecules needed to form RNA and DNA — in fragments of a meteorite that landed in Australia. The molecules didn’t come from Earth; they were present in whatever place the meteorite first formed. Which means that those molecules existed when the solar system formed, some 4.5 billion years ago. Eventually, rocks containing those molecules landed on Earth. It’s not much of a leap of the imagination to see that the ingredients for life could well have been delivered from space, and that we are really and truly “space stuff.”
What this should tell you is that the search for life in the universe isn’t really a search for little green men or cosmic omnisciences. It’s a journey that organic chemistry will lead, and all we have to do is study what it gives us.
June 25, 2008 at 22:07 pm | Leave a Comment
It Began with a Flashlight
Let’s change gears here a bit and extend our gaze out to the stars. Back when I was a kid, somebody told me about light speed. It was on a summer night and we were outside looking up at the stars. To give me an idea of how far away they were, my companion turned on the flashlight we had been playing with, pointed it up to the sky, and flicked it on and off. He explained that in one second, that flashlight beam had traveled 186,000 miles (300,000 kilometers). I couldn’t even begin to wrap my head around the idea at the time. What came next really boggled my mind: even if that light traveled all night, it still wouldn’t have even left the solar system. It would take years to get to the next star, if it got that far.
I played a lot with flashlights (no doubt annoying my parents who had to keep buying batteries for them) trying to figure out how we could send signals to space using them. It didn’t occur to me (because I didn’t know until much later) that most of the light would eventually be absorbed by interplanetary and (and if I was lucky) interstellar dust. So, my signals to beings on distant planets likely will never get very far.
Human beings, however, are sending out other signals that ARE getting “out there.” In fact, the leading edge of that signal “front” is about 75 years away from us. It’s a spherical “front” carrying a steady stream of signals stretching back to the first radio and TV broadcasts to signals that are just now leaving our planet. As it turns out, there are some stars with planets around them that lie inside that expanding sphere of influence. Any beings on those planets who can receive broadcasts are probably trying to puzzle out just what it is we’re trying to tell the universe. And somewhere, lost in all that noise, I’d like to imagine that my feeble little flashlight signals are limping along, telling the cosmos that I said “hi.” (Of course they’re not, but it’s kind of an awe-inspiring thought, anyway…)
June 24, 2008 at 12:26 pm | Leave a Comment
We Didn’t Need Spacesuits, Just Cardboard
AS you might imagine after reading the past few posts, I’ve got Mars on the brain. It’s almost genetic, but not quite. Back when I was a kid, living on a farm in Boulder, Colorado, we had a game we played. I don’t remember the name of the game, but let’s call it “Going to Mars.” This was back before we’d landed folks on the Moon. I’d read somewhere about Mars and since the solar system was in the news, I’m guessing we decided to make a game of it.
We got a big cardboard box and put it out in a field. That was our rocket. We stood in it and made lots of rocket noises like we’d heard on TV during launches. And, after a while, we somehow landed on Mars. Never mind that Mars was basically an alfalfa field. To us, it was Mars. And we explored our Mars and found all kinds of cool things.
When I was a few years old, I read the first of the Edgar Rice Burroughs books about Mars and found out that John Carter basically got to Mars by standing in a cave and teleporting himself there. Very cool… we both got there by imagination, which is great.
Well, about a decade ago, I shared that childhood game with the world in the form of a planetarium show called SkyQuest. It’s about a little girl who grows up to be an astronomer and how she played astronaut games as a child. There’s a short sequence in the show where she builds her rocket and goes to Mars, but most of SkyQuest is about her interest in the stars and planets.
In a way, the show parallels some of my life story, and I’ve had many planetarium folk tell me that it reminded them of cardboard rockets and space exploration games they played as kids, too. What this tells ME is that we need both science education AND imagination to make future astronomers and astronautsA still from SkyQuest, which we created for the Albert Einstein Planetarium at the Smithsonian’s National and Air and Space Museum.
June 23, 2008 at 17:18 pm | 3 Comments
It’s a Question Somebody’s Bound to Ask
They’ve found frozen water on Mars. This is a BIG deal, even though people have known for years that Mars has water locked away in permafrost and as a huge component of one of the polar caps. So, why is the Phoenix Lander’s confirmation of water ice such big news? Because we can reach that ice and study it. As Peter Smith, the principal investigator for the mission told the press a couple of days ago, “The truth we’re looking for is is not just looking at ice. It’s in finding out the mineral, chemicals, and hopefully the organic materials associated with these discoveries.”
Finding out what’s dissolved in the water that made the ice Phoenix is studying will tell Smith and his gang of scientists a great deal about whether Mars has (or ever did have) conditions where life might thrive. You could do the same thing with frozen water here on Earth, and figure out from various dissolved minerals and their abundances (how much of them is in the water) a lot about the life that exists here on our planet and its effect on the environment. Every living thing changes its environment a little (or sometimes a lot), and those changes show up as chemical abundance shifts and (in the case of fossils) in geologic layers, or as organic compounds mixed with soil and rock. Water is part of the equation of life, so confirming its existence with a lander that has an onboard chemical analysis lab is a great leap forward. Now we can melt that ice and study it. I can’t wait to find out what it’s telling us!
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Image of Horsehead Nebula: T.A.Rector (NOAO/AURA/NSF) and Hubble Heritage Team (STScI/AURA/NASA)
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