One often sees in films that the ‘breathable’ air from a spacecraft is sucked out rather ‘violently’ if there is even a slit in the hull. If so, why doesn’t the “vacuum” of space pull our “air” into itself to form some sort of equilibrium?
As far as I know, our atmosphere is not sealed off with a special dome at all.
Is this only due to the gravitational pull of our earth?
Or are there other explanations?
Answer
It is indeed the gravitational pull of the Earth that holds our atmosphere. A spacecraft has so little mass that its attraction is negligible, so it cannot hold air.
The Earth is already struggling. One molecule might dare to move too fast and leave Earth, and it won’t come back. Fortunately, the Earth’s crust also releases gases, partly through volcanism, so that the atmosphere is replenished. The Moon, on the other hand, has too little gravity to hold the atmosphere it once must have had. Mars (about half the size of Earth) also has an atmosphere with a density about one-hundredth the size of ours.
Answered by
Prof. dr. Christopher Waelkens
Astronomy
Old Market 13 3000 Leuven
https://www.kuleuven.be/
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