Asteroid Impact – A double punch from space

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Scientists have found telltale evidence that an asteroid twice as large as any previously known smashed into Earth about 300 million years ago. Previously, the largest asteroid impact was believed to have occurred 66 million years ago, when a massive space rock hit what is now the Yucatan Peninsula in Mexico, causing such havoc that it led to the extinction of the dinosaurs.

But scientists conducting geothermal drilling below the surface of Central Australia recently discovered two vast underground scars of an even more massive asteroid, which broke in two and blasted into Earth from 300 million to 600 million years ago. Testing revealed that the two impact zones—now 19 miles below the surface—were actually caused by the same meteorite.

At more than 250 miles wide, the combined size of the craters suggests that the asteroid was some 12 miles wide—perhaps double the size of the dinosaur-killing asteroid—before it broke in two. The double punch should have raised so much dust that it darkened the skies for years and wiped out most living things, but scientists have no evidence of that. “It’s a mystery,” says lead researcher Andrew Glikson. “We can’t find an extinction event that matches these collisions.”


World's largest ever asteroid impact found in Australia


Scientists in Australia have discovered what they say is the largest asteroid impact area ever found.
The 400-kilometre (250-mile) wide area is buried deep in the earth's crust and consists of two separate impact scars.
The team behind the discovery, from the Australian National University (ANU), said the asteroid broke into two before it hit, with each fragment more than 10km across.
The impact is thought to have occurred at least 300 million years ago.
The surface crater has long since disappeared from central Australia's Warburton Basin but geophysical modelling below the surface found evidence of two massive impacts, said Dr Andrew Glikson, who led the ANU team.
"It would have been curtains for many life species on the planet at the time," said Dr Glikson.
But the team, which published its findings in the geology journal Tectonophysics, has not been able to connect the impact to any known extinction.
"It's a mystery - we can't find an extinction event that matches these collisions," said Dr Glikson. "I have a suspicion the impact could be older than 300 million years."