The most massive stars are the celebrities of the cosmos: they live extravagant lives, 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 within a certain "minimum safe distance” would pose a grave threat to Earthlings. We will discuss these cosmic threats to life and show compelling evidence of a “near miss” supernova from 3 million years ago that rained its debris upon the Earth. This amazing discovery allows us to study supernova ashes in the laboratory and confirms that nearby explosions are a fact of life in our Galaxy. We therefore press further, presenting recent evidence that supernova explosions could have caused biological extinctions on Earth around 360 million years ago. We conclude with tests of this hypothesis, including the search for trace amounts of radioactive supernova byproducts in fossils that witnessed the end of the Devonian period.
Brian Fields is a professor of Astronomy and of Physics at the University of Illinois, and a member of the Illinois Center for the Advanced Study of the Universe. He is fascinated by the "inner space/outer space" connections that link the science at the smallest and largest scales. His research studies the highest-energy sites in nature –-the big bang, exploding stars (supernovae), and high-energy particles in space (cosmic rays) – where nuclear physics and elementary particle physics play a central role. He is particularly interested in the ways exploding stars influence life on earth: supernovae make life possible, but also loom as possible agents of mass extinctions.
