Ancient Earth hammered by double space impact (BBC)
By Paul Rincon
Science editor, BBC News website
We've all seen the films where an asteroid hurtles towards our planet, threatening civilisation.
What's less well known is that menacing space rocks sometimes come in twos.
Researchers have outlined some of the best evidence yet for a double space impact, where an asteroid and its moon apparently struck Earth in tandem.
Using tiny, plankton-like fossils, they established that neighbouring craters in Sweden are the same age - 458 million years old.
Details of the work were presented at the 45th Lunar and Planetary Science Conference in The Woodlands, Texas, and the findings are to be published in the Meteoritics and Planetary Science journal.
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more: http://www.bbc.com/news/science-environment-26172181
