SN 1987A was a type II supernova in the Large Magellanic Cloud, a dwarf satellite galaxy of the Milky Way. It occurred approximately 51.4 kiloparsecs from Earth and was the closest observed supernova since Kepler's Supernova in 1604. From Wikipedia
New research suggests supernova explosions depleted Earth's ozone layer, contributing to the Devonian and Ordovician extinctions.
