Stellar Evolution
All stars form in nebulae, huge clouds of gas and dust.
Though they shine for thousands of years, stars do not last forever. The changes that occur in a star over time and the final stage of its life depends on a star's size.
Eventually, the hydrogen that powers a star's nuclear reactions begins to run out. The star then enters the final phases of its lifetime. All stars will expand, cool and change colour to become a red giant or red supergiant.
What happens next depends on how massive the star is.
Mario Hamuy
Occupation: Astronomer and Professor
Year born: 1960
Stars That Go Bang!
Supernovae are exploding stars which increase in brightness very suddenly and unexpectedly.