By Katherine Kornei
Earth is continuously plowing through extraterrestrial dust. Tens of thousands of tons of the stuff, mostly from asteroids and comets, settles all over the planet every year. We are the shoulder to a universe of dandruff.
But even the faintest detritus has a story to tell. Recently, scientists analyzed dust collected from Antarctic snow and found an excess of radioactive iron. After ruling out contamination from nuclear weapons testing and other sources, the team concluded that the iron was produced by supernovas, fleeting explosions of stars more massive than the sun. This discovery suggests that stellar blasts might have rocked Earth and the rest of the solar system in the not-too-distant past. The results were published on Aug. 12 in Physical Review Letters.
Meteorite hunters are drawn to Antarctica because the space rocks, which are dark, stand out against the snow. Dominik Koll, a doctoral candidate in nuclear physics at the Australian National University in Canberra, appreciates Antarctica for other reasons: its remote location and desert climate, which ensure that whatever extraterrestrial dust falls from the sky remains relatively uncontaminated and undiluted.
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