潜在危险小行星的轨道
(原标题: Orbits of Potentially Hazardous Asteroids)
2023-06-30
浏览次数: 15
小行星危险吗？有些是，但在任何一年里，危险小行星撞击地球的可能性都很低。然而，由于过去的一些大规模灭绝事件与小行星撞击有关，人类已经把寻找和编目那些有朝一日可能影响地球生命的小行星作为首要任务。图为1000多颗已知的潜在危险小行星（PHAs）的轨道。这些记录在案的翻滚的岩石和冰巨石直径超过140米，将在距离地球750万公里的范围内通过，大约是到月球距离的20倍。尽管它们在未来100年内都不会撞击地球——并不是所有的pha都被发现了，而且在过去的100年里，许多轨道变得难以预测。例如，如果这么大的小行星撞击地球，可能会引发危险的海啸。为了研究拯救地球的策略，美国宇航局去年成功地测试了双小行星重定向测试（DART）任务。当然，每天都有小得多的岩石和冰块撞击地球，通常不会造成危险，有时会产生令人难忘的火球和流星。今天是小行星日
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Are asteroids dangerous? Some are, but the likelihood of a dangerous asteroid striking the Earth during any given year is low. Because some past mass extinction events have been linked to asteroid impacts, however, humanity has made it a priority to find and catalog those asteroids that may one day affect life on Earth. Pictured here are the orbits of the over 1,000 known Potentially Hazardous Asteroids (PHAs). These documented tumbling boulders of rock and ice are over 140 meters across and will pass within 7.5 million kilometers of Earth -- about 20 times the distance to the Moon. Although none of them will strike the Earth in the next 100 years -- not all PHAs have been discovered, and past 100 years, many orbits become hard to predict. Were an asteroid of this size to impact the Earth, it could raise dangerous tsunamis, for example. To investigate Earth-saving strategies, NASA successfully tested the Double Asteroid Redirection Test (DART) mission last year. Of course, rocks and ice bits of much smaller size strike the Earth every day, usually pose no danger, and sometimes create memorable fireball and meteor displays. Today is: Asteroid Day