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Lost in space?

作者:虎丙    发布时间:2019-03-03 03:15:10    

By JEFF HECHT in BOSTON An enigmatic object a few metres across with an orbit very similar to the Earth’s will pass about 500 000 kilometres from our planet on 5 December. Astronomers suspect that it is a small asteroid or a lost spacecraft returning from deep space. James Scotti of the Lunar and Planetary Laboratory at the University of Arizona found the object, named 1991 VG, on 6 November with the university’s 0.91-metre Spacewatch telescope. Brian Marsden of the Harvard-Smithsonian Astrophysical Observatory says its orbit is more like the Earth’s than that of any known asteroid: ‘I’ve never seen anything like this before.’ The object’s size and orbit are what would be expected for a spacecraft launched from Earth. But in a search through the launch records, Donald Yeomans of the Jet Propulsion Laboratory in Pasadena could not find anything with a matching orbit. It is unlikely to be a long, thin rocket booster, because such an object would vary in brightness as it tumbled through space. Marsden speculates that 1991 VG may have escaped from the Trojan points in the Earth’s orbit. Trojan points are regions of space 60 degrees ahead and 60 degrees behind the planet. Bodies that wander into these regions are trapped by the Earth’s gravity. Further radar observations could provide a more detailed picture of the asteroid. Observers will probably have to wait until next month,

 

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