Wednesday, March 6, 2013

Shooting star!

Scientists working on the East Antarctic ice sheet have found an 18kg meteorite, the biggest discovered there in the last quarter century. The researchers, from Universities in Brussels and Tokyo, have spent the southern summer collecting meteorites near the Princess Elisabeth Antarctica research base. 

Although meteorites fall randomly all over the globe, they are easier to “harvest” in Antarctica than anywhere else, for a few reasons. First, any rock found on an ice sheet almost certainly fell from the sky, and stands out dark against the white ice. But also, these meteorites become concentrated in certain places by the flows of ice across the huge Antarctic land mass. These flows press up against mountain ranges and then are evaporated by the strong katabatic winds of the arid polar plateau. The meteorites are left behind, and accumulate slowly over the centuries.

The large meteorite found by this season’s team is an “ordinary chondrite”. A rather understated name for a fascinating rock – chondrites are made up of tiny spheres (chondrules) of high-temperature minerals that are thought to have formed at the dawn of the solar system. They are primitive material left over from our origins. The oldest known minerals have been found in chondrites, and it is hoped that this latest find will open new windows on how the solar system evolved when the sun was a very young star.

Image: the discovery of the 18kg chondritic meteorite in East Antarctica (Credit: International Polar Foundation/Vinciane Debaille).


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