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

A molecule would have to have 11 km/s to be able to escape earth’s gravity and head out into interplanetary space. The average speed of molecules at sea level is about 0.5 km/s. Molecules that head toward space slow down, stop, and head back down. A tiny amount have enough energy to escape but it’s a very slow process.

Answer 2

Where’s [Desertphile](https://youtu.be/DutJLb-c0vs?si=nmvo_Wf7lTX8gvGG&t=302) when you need him?