Although stars live for millions or even billions of years, all stars will eventually run out of fuel and die. For small stars like the Sun, this death is gentle, with the star gradually releasing its outer layers to form planetary nebulae.  In larger stars, however, the story is completely different. Rather than a gentle death, these stars end in a spectacular explosion known as a supernova. Supernovae are the means by which heavier elements find their way into new generations of stars: without them, life simply will not exist.