141 Loomis Laboratory

Department of Physics

The most massive stars are the celebrities of the cosmos: they are very rare, but live extravagantly and die in spectacular and violent supernova explosions. While these events are awesome to observe, they can take a sinister shade when they occur closer to home, because an explosion inside a certain "minimum safe distance" would pose a grave threat to Earthlings. We will discuss these cosmic insults to life and present recent evidence that a star exploded near the Earth about 3 million years ago. Radioactive iron atoms have been found in ancient samples of deep-ocean material found around the globe, and also on the Moon. These unique atoms are tiny, telltale samples of debris from the supernova explosion. Thus, for the first time we can use sea sediments and lunar cores as telescopes, probing the nuclear fires that power exploding stars. Furthermore, an explosion so close to Earth was probably a "near miss," which emitted intense and possibly harmful radiation.