Learn the two ways a star can die — quietly (a white dwarf) and explosively (a supernova) — and understand that we are made of stardust.
Two fates of a star
Mass decides everything
A star isn't eternal: sooner or later the hydrogen in its core runs out. What happens next depends on the star's mass.
Stars like the Sun (and lighter ones) go quietly. First the star swells into a huge red giant (our Sun may swallow Mercury and Venus along the way). Then it sheds its outer layers as a beautiful cloud of gas, and what remains in the center is a small hot core the size of Earth — a white dwarf. It no longer produces energy and simply cools slowly for billions of years.
Stars much heavier than the Sun go out with a bang. At the end of their lives, their core suddenly collapses, and a supernova occurs — a colossal explosion. For a few weeks, one such star can shine brighter than an entire galaxy of billions of stars.
Most important: it is in stars and in these explosions that almost all the elements heavier than helium are born — carbon, oxygen, iron, gold. The atoms in your body were once forged inside stars. We are literally made of star stuff.
Lesson notes
Mass decides everything
A star isn't eternal: sooner or later the hydrogen in its core runs out. What happens next depends on the star's mass.
Stars like the Sun (and lighter ones) go quietly. First the star swells into a huge red giant (our Sun may swallow Mercury and Venus along the way). Then it sheds its outer layers as a beautiful cloud of gas, and what remains in the center is a small hot core the size of Earth — a white dwarf. It no longer produces energy and simply cools slowly for billions of years.
Stars much heavier than the Sun go out with a bang. At the end of their lives, their core suddenly collapses, and a supernova occurs — a colossal explosion. For a few weeks, one such star can shine brighter than an entire galaxy of billions of stars.
Most important: it is in stars and in these explosions that almost all the elements heavier than helium are born — carbon, oxygen, iron, gold. The atoms in your body were once forged inside stars. We are literally made of star stuff.