Science & Nature Archive

Friday, January 16, 2009

Life on Mars

My Favorite MartianThis news has already made it around practically all of the science blogosphere, and I even saw it mentioned in a special breaking news type segment on the Science Channel last night, but it's so cool that I can't resist commenting on it.

NASA just announced that they've definitively found methane on Mars. This is the first time they've been positive - previous announcements of methane were tentative, requiring more examination of the evidence. Since methane gets broken down very quickly in the Martian atmosphere (through as yet unknown mechanisms), finding methane means it must have been released into the atmosphere fairly recently. From what I've been able to gather, there are three likely sources for this methane:

  1. Biology This is most exciting possibility, that living organisms beneath the Martian permafrost are creating the methane as waste.
  2. Geochemical While I don't find this quite as exciting as life, it would mean that Mars is still geologically active. There are several processes that this could be.
  3. Reservoir In other words, there's no current process producing new methane. It was previously generated either biologically or geochemically (or both), and became trapped, and all we're witnessing now are periodic leaks.

I'm trying to be reserved about this, since NASA got my hopes up before with the announcement of probable fossil microbes in a Martian meteorite, which turned out to be not as probable as they'd initially thought. It still could be microbe fossils, but it could also be from non-biological sources along with Earthly contamination. So, I'm trying not to get too excited about this announcement.

But, if the methane does turn out to be from biological origin, it means we've found aliens! Granted, life on Mars may be little green slime instead of little green men, but it would still be extraterrestrial life. From Carl Zimmer's blog coverage of the news conference, there were a few statements that do seem to indicate that biology is the most likely source of this methane.

2:18 Mumma points out that if volcanoes were making the methane, you’d expect other gases too, which they don’t see. NASA will look for other things that would be consistent with biology.
2:21 Mumma is explaining some of the backstory–first reports of observations were in 2003. We knew we had methane since late 2003, he says. But they’ve been working to make the data “unassailable.” We’ll see…
2:35 Back to the science: Lisa Pratt says methane from rock (serpentinization) is rare on Earth and actually plugs up active sites. This is why she takes biology seriously as “slightly more plausible.”

There are two possibilities I can think of for this life (if it does indeed turn out to be life):

  1. uses DNA or RNA
  2. uses something else

If the microbes use DNA or RNA, then it would seem extremely likely that they have a common ancestor with life here on Earth. From what I've read, scientists think it's more likely that life would have originated here on Earth, and then got transferred somehow to Mars. Though it's still possible that it went in the other direction - life originating on Mars and then seeding Earth.

If the microbes don't use DNA or RNA, then it would seem most likely that they originated independently from the life here on Earth. Now that would be super exciting. For one, it would mean that life probably is fairly common in the universe, and that we're not all alone. Heck, if so many solar systems have life, then other multicellular and intelligent life out there seems much more likely, maybe even other technologically inclined organisms capable of producing civilizations. However, it will be a long time before we can look into those possibilities. But, the possibility of independent life on Mars is exciting for another reason - it would show us another strategy for life to take. It would start to show what types of things common to life on Earth are that way because they're needed for life, or simply because of historical contingency.

This really is some of the most exciting news I've heard in a while. Now we just have to wait to see what the actual source turns out to be.

Further Reading:

Added 2009-01-19 Phil Plait of the Bad Astronomy Blog has finally weighed in on this topic. He's very reserved about the whole thing, stressing that we don't know exactly what's creating the methane, and that we just need to wait for more data. He also criticizes much of the media for over hyping the biology aspect of the story.

Revised 2009-02-13 to added the statement "(if it does indeed turn out to be life)." That section's been bugging me ever since I first posted this - I should have edited that a while ago.

Thursday, January 15, 2009

Darwin Year Events in Dallas

Charles Darwin as a Young ManI wrote an e-mail to the Dallas Museum of Nature & Science asking them about Darwin Year events. Since the events don't seem to be advertised very prominently on the museum's site, I'll post their response here:

Hi Jeff. We are going to host two events. Cocktails with Charles on his actual birthday 2/12 and cupcakes with Charles on Saturday 2/14. The Thursday event is for adults only and the Saturday event is for families.

I don't think I'll make the two hour drive to to Dallas just for cocktails or cupcakes, but if I just happen to be visiting my wife's family that weekend...

Friday, January 2, 2009

Happy Darwin Year

Charles Darwin as a Young ManSince 2009 marks the bicentennial of Charles Darwin's birth, as well as the 150th anniversary (sesquicentennial) of the publication of On the Origin of Species, many groups have decided that 2009 should be Darwin Year. So, to kick off the year, here are a couple links to good sites dealing with Darwin.

  • Nature's Darwin 200 The prestigious journal has put together a collection of articles, editorials, news stories, and various other essays and features that have to do with evolution in general or Darwin in particular.
  • The Darwin 200 Consortium Hosted by London's Natural History Museum, this site also has a collection of info on evolution, as well as info about upcoming events to celebrate Darwin Year.
  • DarwinDay.org Another good site with evolutionary info. The events on this site are mostly on or around Darwin Day, February 12th.
  • American Museum of Natural History's Darwin page Yet another good collection of information. This is from the exhibit that ran in the museum from 2005 to 2006.

To give a short taste of the Nature site, they've made freely available, and even encouraged dissemination of (so sharing it here is perfectly legal), an article on 15 Evolutionary Gems, collecting information from articles published in the journal "over the past decade or so to illustrate the breadth, depth and power of evolutionary thinking."

Don't forget to check with your own local museums. Even if they don't have any special events scheduled for Darwin Year, they're always fun to visit, anyway.

Added 2009-01-02 Well, I figure that for the kick off to Darwin Year I might as well post links to the previous posts I've made on evolution or Darwin. If I happen to post anything else on the subject during this year, I'll try to remember to update this list.

Friday, November 14, 2008

The Moon

Speaking of space, my daughter and I broke out the telescope tonight, and I figured that just for the hell of it, I'd try to take a picture of the moon. No fancy equipment - just sticking the camera up against the eyepiece, and doing my best to get it in focus.

The Moon
(click image to enlarge)

If anyone's interested, it was an Astroscan telescope, and the box the eyepiece was in said "Plossl F15." The camera was a 7.2 MP Sony DSC-W80. I probably could have gotten a little better picture if I'd messed around a bit more, but I thought this one still turned out decent.

Thursday, November 13, 2008

The Universe Is Big

Douglas Adams once wrote,

Space is big. Really big. You just won't believe how vastly hugely mind-bogglingly big it is. I mean, you may think it's a long way down the road to the chemist, but that's just peanuts to space.

Phil Plait from the Bad Astronomy Blog recently posted about "the deepest ground-based look into the universe ever undertaken." I've put a compressed image below, but I would highly recommend downloading the 32MB full resolution image (The ESO reorganized their site. The image can now be found here. It's offered in several resolutions, including a gigantic 78.6 MB tiff. You could also use this flickr link instead, for a slightly lower res version). Don't be fooled - most of those smudges of light aren't individual stars; they're galaxies.

Deep Look Into Space

Okay, to give an idea of scale, I've superimposed that image onto the moon, to show how much of our field of view it takes up (If you make a thumbs up sign and hold it at arm's length, the full moon's about the size of your thumb nail). Not just that, but notice that little white square in the top left corner of the superimposed image? Well, I put the full size of that portion on the right. Note that in the image above that that region appears to be pretty empty, but once you zoom in on it, you can see there's still a lot there. And remember, those are galaxies, not individual stars. That's why it's so impresive to download the full size image and just scroll around it.

Image Superimposed on Moon

Okay, to put this into a little more perspective, I did a rough calculation. It seems like people like comparing stars to grains of sand. Well, it's been estimated that our galaxy contains around 100 billion (1 x 1011) stars. For a rough calculation, let's assume we have spherical grains of sand around 0.5mm in diameter (source), or about .02 inches in diameter. I won't bore you with the calculations, but 100 billion grains of sand would have a combined volume of 231 cubic feet. Assuming a 64% packing ratio (because there're going to be air spaces in between the grains), you'd actually need a container of around 361 cubic feet to hold all that sand, which works out to a cube of around 7 ft. per side.

So, the point of all that calculation - if you had a 7'x7'x7' container full of sand, that's about how many stars there are in our galaxy. Assuming we have an average size galaxy (some are bigger, some are smaller), just about every smudge of light in the image above represents around that many stars. I really can't even begin to comprehend that - all I can do is describe it. Scrolling around that full size image gives me butterflies in my stomach thinking about just how big this universe is.


Added 2008-11-14 Okay, that assumption about our galaxy being typical has been bugging me a bit. I still haven't been able to find a good source showing the distribution of sizes of galaxies (admittedly, I haven't looked very hard), but Wikipedia says that most galaxies range in size from 10 million to 1 trillion stars. So, repeating the calculations I did earlier with that star count, it would take a 15x15x15 ft cube to hold a trillion grains of sand, and a 4x4x4 inch cube to hold 10 million. Now, a 4" cube may not be all that big compared to the 15' one, but that's still a lot of grains of sand.

Now, just to add one more bit of comparison, if you're in a dark area on a clear night, you could probably see around 2000 individual stars with your naked eye (since you can't resolve individual stars in the Milky Way or 3 three galaxies you can see with the naked eye, the Andromeda Galaxy, The Large Magellanic Cloud and the Small Magellanic Cloud - source1, source 2). It would only take a 1/4 inch cube to hold that many grains of sand.

So now, when you look at the picture, you'll have a slightly more accurate guess of how many stars each one of those smudges of light represents.

I'll also add that after working on this entry yesterday, and then staring up at the night sky with a near full moon for comparison, it made me feel tiny.

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