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

Observing and comparing diffrent stars let us understand the processes in them which make them emitting light and based on the light you could measure in which phase a star is.

This allows us to understand if a star is young, adult or close to the end of its lifetime – all three of course on a cosmic scale