Question

What will happen to the helium in the Sun when the hydrogen begins to run out in the future?

Answer 1

When the Sun runs out of hydrogen to fuse into helium it will become a red giant because the force of gravity can no longer hold the force of fusion at bay. If the temp. rises around 10^8 K, helium begins fusing to create heavier elements like carbon and oxygen. Stars like our Sun do not have enough mass to fuse oxygen and carbon into heavier elements. Once it runs out of helium to fuse it sheds its outer layers, becoming a white dwarf that will slowly fade away over time.