There's dire news for anyone still worried about an asteroid slamming into Earth. Three geologists have proposed that the planet was once hit by at least five giant fragments of a comet or asteroid, within hours of each other.
Ever since the splintered Comet Shoemaker-Levy 9 collided with Jupiter in 1994, scientists have been looking for evidence of such multiple impacts on other celestial bodies. John Spray and colleagues at the University of New Brunswick in Canada now suggest that Earth got a quintuple-whammy in the late Triassic Period.
Five impact craters appear to line up when the continents are reassembled as they lay about 214 million years ago, the scientists wrote recently in Nature. The craters of Rochechouart in France, Manicouagan and Saint Martin in Canada, Obolon in the Ukraine and Red Wing in North Dakota are all of about the right age and position to have been created by a colliding comet or asteroid, they said.
-- Dallas Morning News