Nitrogen is common to all terrestrial atmospheres we currently know of.

Mars has it, though only 3%. The rest is primarily co2.

Venus has it, same figure. If you take away the co2 (the vast majority, and
a primary cause of the intense pressure), you're left with a nitrogen
atmosphere only twice as thick as Earth's, so in most ways that count Venus
has quite a bit of nitrogen with no plant life possible on it.

Earth has a predominantly nitrogen atmosphere, with oxygen making up only a
5th of it and everything else negligible. Much of this is because the far
heavier methane atmosphere we used to have, along with the not
inconsiderable co2 content, have been chemically leeched out by geologic and
biological methods. Had there been no life, we'd have either an almost
entirely nitrogen atmosphere w/ higher co2 levels, or methane would not
break down well and would be a considerable atmospheric component.

Nitrogen appears to be a default when everything else is taken away (in
Earth's case, it's the only gas that isn't being stripped out on a large
scale... in Titan's case, it's the only gas that doesn't precipitate there
that we know of).


"Rodney Kelp" wrote in message
...
Well, we know plants give off nitrogen at night.
What plants are on Titan?
"Paul F. Dietz" wrote in message
...
Rodney Kelp wrote:

How do you get a nitrogen atmosphere from a moon that has methane
oceans?

How do you get a (mostly) nitrogen atmosphere from a planet that has
water
oceans?

Paul