[Congressman Billybob]

I thought methane was a biologic product. I read somewhere that indications of methane in Earth's atmosphere's signature would tell any aliens who visited, thousands or millions of years ago, that there was life on Earth. And the source of that would be termite flatulence, since they were one of the earliest widely prevalent life forms.

Did I miss remember all that?

Congressman Billybob

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[js1138]

Organic in the sense of being a hydrocarbon, but not biologic. You will hear people talking about pre-biological chemistry, but that's another thread.

[Grut]

Did I miss remember all that?

Free oxygen shows the presence of life; oxygen is so active that it soon combines with other elements and disappears from the atmosphere unless it's constantly being renewed by further biological activity. Methane I'm not sure about but I think it's just a garden variety chemical.

[Paleo Conservative]

I thought methane was a biologic product.

Not necessarily. On Earth methane does persist in the atmosphere due to the oxidizing atmosphere. So any methane in the Earth's atmosphere is fairly recent (less than a few thousand years) and most likely of biological origin. The atmosphere of Titan is reducing, so the methane probably dates to the formation of the solar system 4.5 billion year ago. It is thought that the Earth originally had a reducing atmosphere, but photosynthetic algae over billions of years gradually released enough oxygen to cause it to be oxidizing.

[Mad_Tom_Rackham]

Does this mean there are cows on Titan?