Ask A Scientist© Astronomy Archive

Question:  Where does the sun get its fuel?
---John

Answer:  The sun runs on hydrogen, which is what it is made of - it is very
gradually consuming itself! Because the fusion reactions it uses create so much
energy, the sun will continue to shine for a long time - probably another 5
billion years. The fusion (converting hydrogen into helium) occurs only in the v ery deepest part of the
sun, which is extremely hot (millions of degrees), and this heat gradually
filters out to the outer layers which are only a few thousand degrees, and this
heat is then radiated into space as light.
Asmith