By PHIL PLAIT - BAD ASTRONOMY
Added: Tue, 08 Jun 2010 13:58:31 UTC

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There has been a bit of an uproar the past day or so that scientists have found evidence of life on Saturn’s giant moon Titan. As soon as I saw the press release I knew this was going to be a problem. So let’s be clear:

First, have we found life on Titan? No.

Have we found evidence that there might be life on Titan? Sorta. The results are preliminary and not yet confirmed; in fact, some of the evidence is from computer modeling and has not been directly observed.

Bear in mind as well that evidence is not proof. Evidence just means an observation was made that is consistent with life on the moon, but doesn’t say much else. There are non-biological explanations for the observations as well.

Of course, speculation is running rampant, so much so that Chris McKay, an exobiologist who studies Titan, has released an article clearing things up.

First, a little background. Titan is a monster, the second biggest moon in the solar system at 5150 km (3200 miles) in diameter. If it weren’t orbiting Saturn, it would probably be considered a planet in its own right: it’s bigger than Mercury and Pluto. It has a thick atmosphere, made up of nitrogen, methane, and other molecules. It’s very cold, but it’s known that lakes, probably of liquid methane, exist on the surface.

Five years ago, McKay and other scientists pointed out that if methane-based life existed on Titan, it might be detectable through a surface depletion of ethane, hydrogen, and acetylene. New observations show that this is the case; there are lower amounts of these substances than the chemistry of Titan would indicate.

As McKay points out, "This is a still a long way from ‘evidence of life’. However, it is extremely interesting."
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TAGGED: BIOLOGY, SPACE