Is our moon's gravitational field strong enough to
retain a gaseous envelope and is there a gas with a sufficiently high
molecular weight that could be used to create an 'atmosphere' for our moon?
Asked by: David Kronick
Our moon has what is called a transient atmosphere.
There is gas on the moon but it is in such a small
quantity that it really doesn't even count as an
atmosphere. As to your question, their is no gas
that can provide a permanent atmosphere to the moon.
Imagine the moon had an atmosphere similar to Earth's.
The sun would heat up the air molecules giving them more kinetic energy
This would cause them to move faster, and faster
until eventually they would reach escape velocity
and leave the planet. The moon's escape velocity
is very small, and thus even a small amount of energy will make
gas on the moon escape from its gravity.
Even the earth is constantly bleeding gas out into space, we
just replenish our air supply through biological processes,
and the occasional asteroid impact that brings in
Answered by: Mike Perkins, Physics/Astronomy Major, Penn State
'Physicists like to think that all you have to do is say, these are the conditions, now what happens next?'