 The asteroid would have looked something like this from http://scrapetv.com/
May 27, 2010 5:15 PM
Crater in Timor Sea
Siberia's crater weighs in as the largest asteroid strike on Earth, at 100km, but the crater discovered by the ANU has so far only been measured according to the width of the base of the mountains surrounding it.
The biggest - Mount Ashmore - measures 50km at its base, according to ANU extraterrestrial impact specialist Dr Andrew Glikson.
"The minimum size of the Mount Ashmore dome ... is 50km at the base, but the full size of the impact crater - not yet defined - may be significantly larger,” Dr Glikson said.
Only one other crater compares to the pair - the 85km wide Chesapeake Crater in the ocean floor off Virginia, USA.
Dr Glikson said the asteroid hit the Earth during a period of intense bombardment 35 million years ago.
Its strike coincided with a sharp fall in global temperatures which in turn preceded the formation of the Antarctic ice sheet.
Both the Siberian and Chesapeake asteroids hit at roughly the same time.
At the same time, Dr Glikson said molten rock fragments rained down on north-east North America, thrown out from the asteroids by the impact of the strike.
And a million years later, the Drake Passage cut South America off from the Antarctica land mass, providing a constant flow of water around the ice sheet already forming as the Earth cooled in the shade of the dust thrown up by the bombardment.
Dr Glikson's research has been published in the Australian Journal of Earth Sciences.
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