In case you haven't heard yet, today NASA announced the definitive discovery of methane on the planet Mars. Why is this significant?
1.) Methane is a known by product of life. (Mars farts, as it were...)
2.) Methane can be broken down easily by basic chemical processes; if there were no life on Earth, our atmospheric methane would disappear in about 10 years. This means that the methane on Mars must come from active processes; it has not been hanging around for millions of years.
3.) Methane can also be a food source for certain types of life.
4.) The presence of methane implies the presence of water; the two processes we know of which produce methane (volcanic activity and life) both require water to supply the hydrogen atoms in methane.
5.) Though volcanic activity can produce methane, there has been no sign that any volcanic activity has occurred on Mars for millions of years— no geologically recent lava flows, no fault lines, nothing.
So, we have methane, no evidence of recent geological activity, and only two known sources which can produce the gas. Either there's volcanic activity going on which we haven't detected (and don't see other evidence for), or a natural non-living process to make methane which we don't know about, or something on Mars is alive.
Now that is some seriously cool news.
--- Howard Shirley
For more, go here: Methane on Mars