Stars have life spans just like people. High mass stars have strong gravity making them extremely hot, so they shine very brightly and exhaust their fuel quickly, within a few million years. Then they expire in spectacular explosions called supernovae. Less massive stars like our Sun shine less brightly, but they last for billions of years. They end their days by ballooning into a red giant star that eventually blows away its outer layers and collapses into a stellar cinder called a white dwarf.