Expert: Philip Stahl - 1/14/2006

Question
Phil,
One of my  grandsons has asked me why methane is abundant in the cosmos?....

It really has me stumped as I was lead to believe that methane came from vegitation/cows/coal etc.
in other words I always thought it came from living matter...

Obviously wrong wrong....

Could you please enlighten me?

Thanks
Barrie Bentley
Nappanee IN

Answer
Hello,

Most of the methane detected in the cosmos probably comes originally from molecular clouds associated with interstellar nebulae. Often - what we call "dark nebulae" (e.g. the Coal Sack in the constellation Crux) are especially abundant in these molecules (many organic) which include: molecular hydrogen (H2), hyroxyl radicals (OH-), hydrogen cyanide (HCN), METHANE (CH4), formaldehyde ((H2 CO), formic acid (HCOOH), methyl alcohol (CH3 OH), methylamine (CH3 NH2) and ethyl cyanide (CH3 CH2 CN).

The carbon abundance would have arisen from the expelled matter in the cores of stars that - at some point- had undergone helium fusion:

e.g.

He4 +  He4  + He4  ->  C 12

(in compacted, simplified form)

then possibly shed carbon layers in a supernova explosion. The residue forming the molecular clouds in their wake.

A final note: methane is not abundant per se in the *cosmos*  - it is in *molecular clouds* for the reason given.

In terms of overall elemental abundance in the cosmos, the ratio of hydrogen to helium predominates and it is 10:1. (e.g. 10 hydrogen atoms to every one for helium). Carbon is about seventy times LESS abundant than helium, hence the potential to form methane is roughly that much less.

In *organic environs*, however, obviously methane will be much more abundant than in the cosmos as a whole