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POPSNew clues on "The Great Dying" The lessons of the Permian-Triassic massacre are "directly applicable to the present," said John Isbell, a geoscientist at the University of Wisconsin in Milwaukee. He said the world today is in danger of exceeding a CO2 "threshold" that could set off an environmental upheaval as great as the one 251 million years ago.
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POPSEarth could seed Titan with life Dr Gladman's team calculated that up to 20 terrestrial rocks from a large impact on Earth would reach Titan. These would strike Titan's upper atmosphere at 10-15 km/s. At this velocity, the cruise down to the surface might be comfortable enough for microbes to survive the journey.But the news was more bleak for Europa. By contrast with the handful that hit Titan, about 100 terrestrial meteoroids hit the icy moon. "It's frustrating if you're a microbe that's been wandering the Universe for a million years to then die striking the surface of Europa," Dr Gladman mused.Asked after his presentation by one scientist whether he thought microbes would be able to survive Titan's freezing temperatures, Dr Gladman answered: "That's for you people to decide, I'm just the pizza delivery boy."
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POPSthe Tunguska event On June 30, 1908, a ball of fire exploded about 6 miles (10 kilometers) above the ground in the sparsely populated region, scientists say. The blast released 15 megatons of energy—about a thousand times that of the atomic bomb dropped on Hiroshima—and flattened 770 square miles (2,000 square kilometers) of forest. The basin of Lake Cheko is not circular, deep, and steep like a typical impact crater, the scientists say. Instead it's elongated and shallow, about 1,640 feet (500 meters) long with a maximum depth of only 165 feet (50 meters).
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POPSComet may have cause mammoth extinction New scientific findings suggest that a large comet may have exploded over North America 12,900 years ago, explaining riddles that scientists have wrestled with for decades, including an abrupt cooling of much of the planet and the extinction of large mammals.