The Guardian reported on Thursday (19-Aug) about newly discovered craters in Antarctica:
Scientists using satellites have mapped huge craters under the Antarctic ice sheet caused by an asteroid as big as the one believed to have wiped out the dinosaurs 65m years ago.Antarctic craters reveal asteroid strike [Guardian]
Professor Frans van der Hoeven, from Delft University in the Netherlands, told the conference that the evidence showed that an asteroid measuring between three and seven miles across had broken up in the atmosphere and five large pieces had hit the Earth, creating multiple craters over an area measuring 1,300 by 2,400 miles.
The effect would have been to melt all the ice in the path of the pieces, as well as the crust underneath. The biggest single strike caused a hole in the ice sheet roughly 200 by 200 miles, which would have melted about 1% of the ice sheet, raising water levels worldwide by 60cm (2ft).
New Asteroid Threat to Earth [about.com]
Near Earth Objects - Are We In Danger? [about.com]