WATCH: Elements - A Brief Big History (H2)

NARRATOR: This star, several times more massive than our sun, is an element factory. Inside the star, gravity and heat crush and restructure atoms, forming elements including metals like aluminum and iron that will spread out into the cosmos when the star collapses and explodes as a supernova. The supernova's energy transforms more atoms. CRAIG BENJAMIN: In this process, all of these other elements are cooked up, if you like, including silver. NARRATOR: But supernovas don't make gold. These do: the ruins of two supernovas, each half a million times more dense than the Earth. They're called neutron stars, and when they collide, they release more energy than our sun releases in its lifetime, creating elements heavier than silver, including gold. But these collisions are rare. There are far more supernovas... ...which is why there's more silver than gold in the Universe and on Earth.