3 ms·

As far as we know, molecules and atoms escaping into space comes due to the solar wind. Somehow the solar wind activates these atoms and carries them off into t

As far as we know, molecules and atoms escaping into space comes due to the solar wind. Somehow the solar wind activates these atoms and carries them off into the distant vacuum, ad infinitum presumably though (I would imagine) limited by the heliopause. [edit, benefiting from convo: mechanisms on atmospheric escape, to varying degrees of verification) • https://en.wikipedia.org/wiki/Atmospheric_escape https://en.wikipedia.org/wiki/Atmospheric_escape • https://en.wikipedia.org/wiki/Hydrodynamic_escape https://en.wikipedia.org/wiki/Hydrodynamic_escape ] Absent that, our treasured atmospheric molecules would have to autonomousy achieve escape velocity, some 22 km/sec , with no outside assistance. A difficult feat. And so, resident atmosphere.

Panzerschrek 1y ago
With high enough temperature some molecules may achieve velocities enough to escape. The question is - how hot was it really? The initial collision happened at least with escape velocity, so there was roughly enough energy for volatiles an non-volatiles to escape. But non-volatiles condensed presumably pretty quickly (but were still hot) in comparison to volatiles.
- ricksunny 1y ago
  Yes I was being a bit too glib in relegating atmospheric escape mechanisms exclusively to action by the solar wind. Lot of proposed mechanisms, uncertain how many of them are verified and quantified to what magnitude. https://en.wikipedia.org/wiki/Atmospheric_escape https://en.wikipedia.org/wiki/Atmospheric_escape https://en.wikipedia.org/wiki/Hydrodynamic_escape https://en.wikipedia.org/wiki/Hydrodynamic_escape As a layperson I see our current epistemological state as long on models, and short on empirical verification (because we're talking about a difficult phenomenon to verify). I think I mostly wanted to offer counterpoint to the original comment that 'this atmosphere can't stay long' i.e. even under elevated temperatures. (I'll probably update my prev comment with those wikipedia links.)

Panzerschrek 1y ago

With high enough temperature some molecules may achieve velocities enough to escape. The question is - how hot was it really? The initial collision happened at least with escape velocity, so there was roughly enough energy for volatiles an non-volatiles to escape. But non-volatiles condensed presumably pretty quickly (but were still hot) in comparison to volatiles.

ricksunny 1y ago
Yes I was being a bit too glib in relegating atmospheric escape mechanisms exclusively to action by the solar wind. Lot of proposed mechanisms, uncertain how many of them are verified and quantified to what magnitude. https://en.wikipedia.org/wiki/Atmospheric_escape https://en.wikipedia.org/wiki/Atmospheric_escape https://en.wikipedia.org/wiki/Hydrodynamic_escape https://en.wikipedia.org/wiki/Hydrodynamic_escape As a layperson I see our current epistemological state as long on models, and short on empirical verification (because we're talking about a difficult phenomenon to verify). I think I mostly wanted to offer counterpoint to the original comment that 'this atmosphere can't stay long' i.e. even under elevated temperatures. (I'll probably update my prev comment with those wikipedia links.)