False color image of Cassiopeia A using Hubble and Spitzer telescopes and Chandra X-ray Observatory. Credit: NASA/JPL-Caltech
An international team of scientists has found evidence of a series of massive supernova explosions near our solar system, which showered Earth with radioactive debris. The scientists found radioactive iron-60 in sediment and crust samples taken from the Pacific, Atlantic and Indian Oceans. The iron-60 was concentrated in a period between 3.2 and 1.7 million years ago, which is relatively recent in astronomical terms.
“We were very surprised that there was debris clearly spread across 1.5 million years,” said Dr Wallner, a nuclear physicist in the ANU Research School of Physics and Engineering. “It suggests there were a series of supernovae, one after another...
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