Radioactive plutonium from a nearby supernova found on Earth

Two and a half million years ago, a cosmic catastrophe unfolded not far from Earth.

In a cluster of young stars just over a hundred light years away, a particularly massive star ran out of fuel. It had gone through its supply of hydrogen, helium, carbon, even oxygen, neon, and silicon. Its core was iron, and that cannot be fused to make energy. The core collapsed, generating a wave of energy so colossal it ripped through the octillions of tons of outer layers of the star, ripping it apart, and ...