An anonymous reader quotes a report from Gizmodo: An unusually large asteroid Crater measuring 19 miles wide has been discovered under a Continental Ice Sheet in Greenland. Roughly the size of Paris, it's now among the 25 biggest asteroid craters on Earth. An iron-rich asteroid measuring nearly a kilometer wide (0.6 miles) struck Greenland's ice-covered surface at some point between 3 million and 12,000 years ago, according to a new study published today in Science Advances. The impact would've flung horrific amounts of water vapor and debris into the atmosphere, while sending torrents of meltwater into the North Atlantic -- events that likely triggered global cooling (a phenomenon sometimes referred to as a nuclear or volcanic winter). Over time, however, the gaping hole was obscured by a 1,000-meter-tall (3,200-foot) layer of ice, where it remained hidden for thousands of years. Remarkably, the crater was discovered quite by chance -- and it's now the first large crater to be discovered beneath a continental ice sheet.

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