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发帖数: 298 | 1 April 4, 2002 | A kilometer-size asteroid, whose whereabouts have been
unknown since just after its discovery 52 years ago, has suddenly reemerged
as an object that may pose a significant threat to Earth in the distant
future. Astronomers at Lowell Observatory rediscovered the wayward object,
known as 1950 DA, by accident on New Year's Eve 2000, and three months later
teams of radar astronomers pinged it from Goldstone, California, and Arecibo,
Puerto Rico. When orbital dynamicists combined the |
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