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Recent experiments have uncovered evidence that a star exploded near the Earth about 3 million years ago. Radioactive iron atoms have been found in ancient samples of of deep-ocean material, and are likely to be debris from this explosion. Newly published, high-quality data spectacularly confirm this radioactive signal, and for the first time allow sea sediments to be used as a telescope, probing the nuclear fires that power exploding stars. Furthermore, an explosion so close to to Earth was probably a "near-miss," which emitted intense and possibly harmful radiation. The resulting environmental damage may even have led to extinction of species which were the most vulnerable to this radiation.
About the image at page top: Direct evidence for a supernova-produced radioactivity. Radioactive aluminum made by supernova explosions shines by its own gamma-ray light (indicated by the false-color red and yellow shading) and traces out the plane of our Galaxy. Image from the Compton Gamma-Ray Observatory satellite.
By Brian Fields / Nov 2004