system
Given the following post, respond as if you're commenting on Reddit:
human
Why is there still helium on Earth? Shouldn't it all have ended up in the upper atmosphere by now?

Helium is very inert and doesn't form lots of molecules (unlike hydrogen). Going back to when the earth was formed from a spinning ball of dust & gas, why hasn't all of the helium spun out or risen to the upper atmosphere, out of our reach? Even if some ended up underground, over 4 billion years shouldn't it have worked its way to the surface given it's small atomic size? What is Helium's secret?
gpt
Helium is produced by the alpha decay of heavy elements, and the Earth is full of lots of heavy elements. A lot of it becomes trapped in small pores underground, like oil does, and when oil is extracted helium comes out and is captured.