[ti:Study: Dinosaur Killing Asteroid Hit Earth at ‘Deadliest Possible’ Angle] [by:www.51voa.com] [00:00.00]更多听力请访问51VOA.COM [00:00.04]A new study suggests the asteroid that killed almost [00:05.48]all the dinosaurs struck Earth at the "deadliest possible" angle. [00:13.20]Scientists believe the asteroid hit Earth about 66 million years ago [00:21.20]near what is today Mexico's Yucatán Peninsula. [00:27.36]The force of the massive crash is estimated [00:32.24]to have been equal to the strength of about 10 billion nuclear bombs. [00:40.36]The climate-changing event is blamed for causing the disappearance [00:46.48]of more than 70 percent of plant and animal life. [00:52.76]All dinosaurs that were not bird-like died out. [00:58.48]What has remained a mystery for scientists, however, [01:03.12]is whether the asteroid strike was a direct hit. [01:08.40]The new study provides evidence that the strike [01:12.76]resulted in the worst kind of crash for the dinosaurs. [01:19.24]Researchers examined data on the structure of the 200-kilometer-wide crater [01:26.72]in Mexico where scientists believe the asteroid hit. [01:32.44]They attempted to recreate the asteroid event on computers. [01:40.08]The results, recently published in Nature Communications, [01:45.24]showed that the asteroid struck Earth at an angle of about 60 degrees. [01:54.32]As a result of the angle, an especially large amount of climate-changing gases [02:01.44]would have been released quickly into the atmosphere. [02:06.88]The lead researcher was Gareth Collins, of Britain's Imperial College London. [02:15.52]"For the dinosaurs, the worst-case scenario [02:19.68]is exactly what happened," he said in a statement. [02:25.04]He added that the release of gases into the atmosphere started a series of events [02:32.56]that led to the permanent disappearance of the dinosaurs. [02:38.60]The release "was likely worsened by the fact that it struck [02:43.80]at one of the deadliest possible angles," Collins said. [02:50.44]If the asteroid had hit head-on or at lower angles, [02:55.44]less material would have been released into the atmosphere, he added. [03:02.36]Scientists believe the massive release of gases and chemicals [03:07.72]into the atmosphere led to a period of extreme cold, also known as a "nuclear winter." [03:17.88]This was caused by large amounts of sulphur particles [03:22.52]that stayed in the air, blocking heat from the sun. [03:28.72]The asteroid strike is also believed to have caused widespread wildfires, [03:35.32]earthquakes and ocean waves, or tsunamis. [03:41.92]The researchers said their models are the first to reproduce the whole event [03:48.80]– from the first hit to the moment when the final crater was formed. [03:55.48]The findings seem to disprove a long-standing theory [04:00.56]that the asteroid moved toward Earth from the southeast. [04:06.56]The scientists said recreations based on the crater's structure [04:12.40]showed the asteroid coming from the southwest. [04:18.04]The study could lead to a greater understanding [04:21.80]about how craters are formed in general. [04:26.52]The modeling suggested, for example, that rocks "rebound" [04:31.68]to fill in beneath the crater during its final formation. [04:37.96]The researchers said the findings suggest that large craters [04:43.36]can be formed in a matter or minutes. [04:47.72]Scientists continue to question how some living things [04:52.44]were able to survive the asteroid event. [04:57.84]Gareth Collins said the new study clearly suggests the strike [05:03.48]resulted in "a very bad day for the dinosaurs." [05:09.12]He added: "It makes it even more remarkable [05:13.40]that life survivedand recovered as rapidly as it did." [05:19.44]I'm Bryan Lynn. 更多听力请访问51VOA.COM