Thirty years ago today, scientists caught the ghosts of an exploding star. The discovery helped confirm how the star died, and the kind of corpse it likely left behind.

Supernova 1987A was the brightest and closest supernova in centuries. It exploded in a small galaxy that’s about 165,000 light-years away.

Theory said the explosion took place when the star’s core could no longer produce energy from nuclear reactions. Without that radiation to push outward, the core collapsed. The star’s outer layers fell inward, then rebounded and blasted into space, forming the supernova.

The collapsing core was squeezed so tightly that electrons and protons were smashed together to form neutrons and neutrinos. The neutrons stayed in the core, forming a super-dense neutron star.

But the neutrinos raced outward. These ghostly particles almost never interact with other matter. The core’s collapse should have produced so many of them, though, that if even a tiny percentage interacted with the surrounding layers of gas, they’d help power the supernova. The rest would race into space unimpeded — including many aimed at Earth.

And on February 23rd, 1987, detectors on Earth caught a couple of dozen neutrinos from the supernova — a huge haul. A few hours later, the light from the blast reached Earth as well. The neutrinos matched what the theory predicted — helping to confirm what happens deep in the heart of a supernova.

More tomorrow.

Script by Damond Benningfield