Hi Eliana,

When the sun burns through all of its hydrogen and helium it will become a white dwarf, which is sort of a "retired star". So, although it's not really being replaced by another star, it is turning into a different type of star which doesn't radiate like the sun does now. At the point when the sun "burns out", the Earth may not even exist because during the process of turning into a white dwarf, the sun will go through a stage called a "red giant" where it will swell and swallow the inner planets before it collapses into its final "retired" stage. Don't worry though- this won't happen for billions of years!

Holly