Eli5: how does the earths atmosphere work? E. G how does the oxygen not fade away into the cosmos

Question

I’ve had a conversation with a guy that claimed “it’s a myth”. An obvious face-palm, I know, but I realized I’d like to know.

In: 71

Answer 1

Imagine that there is no atmosphere at all. Just one little oxygen molecule bouncing on Earth’s surface like a bouncy ball. How high does it bounce?

Well, at room temperature it’s moving around 330 m/s, which would let it bounce something like five kilometers up.

This is what the very top of the atmosphere looks like. Radiation from space *does* blast some of it away, but most of it just curves back down.