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

Earth’s gravity and the magnetic field.

The atmosphere can’t just float away for the same reason we can’t just jump off. Gravity is tying us down.

The sun is constantly spewing out high energy particles, aka solar wind. The earth’s magnetic field protects the atmosphere from mostly getting blown away.

Lighter elements, like helium, can float high enough to be blown away though.