Eli5: How are scientists able to determine the lifetime of the sun and other stars? Are the reactions that happen within stars reproducible in a lab?

Question

Eli5: How are scientists able to determine the lifetime of the sun and other stars? Are the reactions that happen within stars reproducible in a lab?

In: Physics

Answer 1

In physics you have what called degeneration, meaning that the matter contained in the sun is always reacting (hence the nuclear reactions you might have heard about; the sun is a bid nuclear reactor) so the matter that’s composing it consumed. But this matter is not infinite.

Knowing the mass of the sun and its composition, you can calculate it’s remaining lifetime.