There could be an oxygen atmosphere without life for a short period of a planet’s history (I’m not sure how long.) It wouldn’t be possible for it to remain permanently.
According to our evidence, Mars had liquid water for a very long period, but no one considers this to be proof that there was life there.
According to our evidence, Mars had liquid water for a very long period,
I went to check this—maybe liquid water is a short-term enough thing that its mere presence is still weak evidence for an active biosphere, but apparently one timeline puts liquid water as present in large quantities for >600 million years. Bleh.
There could be an oxygen atmosphere without life for a short period of a planet’s history (I’m not sure how long.) It wouldn’t be possible for it to remain permanently.
According to our evidence, Mars had liquid water for a very long period, but no one considers this to be proof that there was life there.
I went to check this—maybe liquid water is a short-term enough thing that its mere presence is still weak evidence for an active biosphere, but apparently one timeline puts liquid water as present in large quantities for >600 million years. Bleh.