Why doesn’t the atmosphere (air we breathe) just float off into space?
Some objects in space have atmospheres like Earth and Jupiter. Others like asteroids and the moon don’t have an atmosphere.
Why doesn’t earth atmosphere just drift away into space?
What am I missing about the concept of atmosphere?
In: Planetary Science
One added point.
All the comments on gravity are correct and covered that well. I have no need to add to that.
I just want to point out that we often mistakenly think of the atmosphere as a blanket of gas that has a distinct upper edge. A stopping point. This may contribute to wondering why the atmosphere doesn’t just drift away. However, that’s not true. There isn’t really an edge to the atmosphere. The atmosphere gradually gets thinner and thinner out to about 10,000km. There it eventually becomes so thin it’s indistinguishable from ’empty’ space. It doesn’t do much stop as far away.
The international space station orbits at a mere 408km up. It is constantly experiencing drag and slowing down. It needs occasional boosts.
What you’ll often hear called the edge of space is something called the Karman line. It’s about 100km up. Really it’s just the point where the atmosphere is no longer thick enough to scatter light and make the sky blue. It’s where you get to see stars even in the day. But there’s still plenty of atmosphere there. Enough to measure.
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