If you want to make a human from scratch, you’ll need to start with a massive star. The next step takes hundreds of thousands of years - you have to wait for the star to die in a violent explosion.

From one of the most cataclysmic events in the cosmos comes all of the beauty we see here on Earth. Life (and even Earth) wouldn’t have formed without them!

You Are Made of Stardust

From the iron in your blood to the calcium in your bones, the elements in your body were forged in the fiery hearts and deaths of massive stars. If we could rewind the universe to close to the beginning, we’d see a sea of hydrogen (about 75%) and helium (about 25%) permeating the cosmos. The first generation of stars formed from this material and began the process of nuclear fusion in their cores to produce more elements.

But there’s a cutoff point to this manufacturing process. Only elements up to iron (the 28th element on the periodic table) can be formed in the cores of stars - but there are over 100 elements! So where did the rest come from? Supernovas.

The Making of a Supernova

Stars spend the majority of their lives fusing hydrogen into helium - a process that creates enormous amounts of energy, yielding a lot of outward pressure. Usually this pressure is balanced by gravity, so the star doesn’t just fly apart. But eventually the star will run out of fuel and its nuclear processes will die down, completely throwing off the star’s balance.

The result? An explosion!

Supernova! Credit: NASA Ames/STScI/G. Bacon

Bright Lights in a Dark Sky

Supernovas can also occur in binary, or double-star, systems when a white dwarf (the core of a medium-mass star that ran out of fuel) steals material from its companion. This, too, throws everything off balance and leads to a giant supernova explosion.

Galaxies are made up of hundreds of millions to hundreds of billions of stars, but a supernova can briefly outshine all of them. These extreme events create elements like gold, mercury, copper and lead. We rely on many of the elements that supernovas produce to form everything from planets to people.

New life is born from the ashes of stars.

A compilation of supernova remnants. Credit: images from NASA, gif'd by the author

Will the Sun Go Supernova Someday?

No - the Sun is destined to experience a much more gentle fate. In 4 or 5 billion years, the Sun will run out of its nuclear fuel. It will swell up (possibly so much that it encompasses Earth’s orbit) and produce a beautiful nebula when it casts off its outer layers, sterilizing the planets. Ultimately, all that will be left is the small skeleton of a star that once made life on Earth possible.