小行星对地球有危害吗？有一些会的，但一颗危险的小行星在任一特定年份撞击地球的可能性都很低。由于历史上的一些大规模灭绝事件与小行星撞击有关，人类仍然把搜寻并编录那些未来可能影响地球生命的小行星作为优先事项来考虑。上图是超过1000颗具有潜在威胁的小行星（PHAs）轨道，所记载的这些在太空中翻滚的巨型石块或冰块的宽度均超过140米，而且都在离地球750万公里（约是地月距离的20倍）的范围内掠过。虽然在未来100年内这些小行星都不会撞向地球，但我们还并未发现所有有潜在威胁的小行星，而且许多小行星在100年后会变得更加难以预测。上述大小的小行星如果撞上地球肯定会有较大影响，比如很可能会引起危险的海啸。当然，比这小的多的石子和冰块每天都有许多撞入地球，但它们通常没有危害，偶尔还会形成火流星或流星雨。
更多天文精彩文章请关注网易博客小组：天文爱好者。
Explanation: Are asteroids dangerous? Some are, but the likelihood of a dangerous asteroid striking the Earth during any given year is low. Because some past massextinction 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 above 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. Of course rocks and ice bits of much smaller size strike the Earth every day, usually pose no danger, and sometimes creatingmemorable fireball and meteor displays.
每日天文一图（APOD）是美国宇航局天体物理学部每日定期发布的天文图片，并配有专业的简短解释，是小子时常光顾的地方，地址为：http://apod.nasa.gov/apod/。现将部分酷图转来并对原文解释做了翻译，英文及天文知识均有限，译错之处敬请各位指正。
秋天的麦兜 2013年8月12日。
评论