About 4.6 billion years ago, a cloud of gas and dust that eventually formed our solar system was disturbed. The ensuing gravitational collapse formed the proto-Sun with a surrounding disc where the planets were born. Now, forensic evidence from meteorites provides conclusive evidence that a low-mass supernova was the trigger.
An international team of scientists has found radioactive iron-60 in sediment and crust samples taken from the Pacific, Atlantic and Indian Oceans. They report that a series of massive supernova explosions occurring between 3.2 and 1.7 million years ago from stars less than 300 light-years away showered the Earth with radioactive debris.