Evidence for Nearby Supernova Explosions

Supernova (SN) explosions are one of the most energetic—and potentially lethal—phenomena in the Universe. We show that the Scorpius-Centaurus OB association, a group of young stars currently located at $\sim 130\mathrm{pc}$ from the Sun, has generated 20 SN explosions during the last 11 Myr, some of them probably as close as 40 pc to our planet. The deposition on Earth of ${}^{60}\mathrm{Fe}$ atoms produced by these explosions can explain the recent measurements of an excess of this isotope in deep ocean crust samples. We propose that $\sim 2\mathrm{Myr}$ ago, one of the SNe exploded close enough to Earth to seriously damage the ozone layer, provoking or contributing to the Pliocene-Pleistocene boundary marine extinction.