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
It’s very not intuitive but every object, from the biggest boulder to the tiniest sand is falling towards earth at the same speed.
Air is made of molecules and molecules are tiny objects. They too fall towards earth. If there were just one molecule of air, it would free fall.
Now in fact there’s a lot of air and they block each other from free fall. It’s because they bounce back and forth so if a molecule would fall towards earth, it will eventually hit another molecule and bounce back. And because the hit is not necessarily on a straight line, they may bounce in an angle like pool balls.
So the atmosphere as a whole is a continuous fall-bounce state but gravity makes sure that the fall part is always there. That’s why there’s more air doing this fall-bounce closer to earth and so the air goes thinner as you go higher.
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