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科学美国人60秒:未知星球-托福听力下载

2017-01-04 12:09:52来源：科学美国人60秒

点击查看>>科学美国人60秒音频：未知星球

　　科学美国人60秒中英文翻译：未知星球

　　科学美国人60秒英文文本

　　This is Scientific American 60 Secomds, Space. I'm Clara Moskowitz, got a minute?

　　Solar system conspiracy theorists have long harbored suspicions that a hidden extra planet or dwarf star lies beyond the orbit of Pluto. As a planet, it’s been called Tyche or simply Planet X. As a star, Nemesis.

　　未知行星.jpg

　　But an exhaustive search has found no hints of this long-rumored object. NASA's Wide-Field Infrared Survey Explorer has scanned the entire sky in infrared light—twice—and ruled out any hidden bodies larger than Saturn out to 10,000 times the distance from the Earth to the sun.

　　Furthermore, it found no evidence for anything bigger than Jupiter out to 26,000 times the Earth-sun distance. Pluto, for comparison, lies only 40 times farther from the sun than Earth.

　　The finding deals a blow to theories that a Planet X- or Nemesis-type object may have caused periodic mass extinctions on Earth. Some theorists have mused that a hidden planet might have swept through bands of comets in the solar system, sending them crashing into Earth. Now it seems that for such mass species die-offs, the fault lies not in the stars.

　　Thanks for the minute for Scientific American 60 Secomds, Tech. I'm Clara Moskowitz.

　　中文翻译请点击下一页

本文关键字: 科学美国人60秒 科学60秒下载 托福听力

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