Lindley Johnson, head of the near-Earth object program at NASA headquarters in Washington, D.C., says an asteroid the size of a football field could wipe out a major city.

在华盛顿的美国宇航局总部的近地天体计划负责人林德利-约翰逊说，如果一颗足球场大小的小行星撞上了地球，其威力可以毁灭一座大型城市。

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The Near-Earth Object Observation Program, commonly called "Spaceguard, " also plots the orbits of these objects to determine if any could be potentially hazardous to our planet.

近地天体观察项目，常被叫做“太空警卫”，也对这些天体绘制了轨道图来判断其中是否有天体可能对我们的星球有潜在危险。

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This estimate was alarming; it was the first time an asteroid had been promoted to "Level 4" on the Torino Scale -- a near-Earth object (NEO) impact hazard categorization method.

这样的预测令人担忧，这是在评价近地天体（NEO）撞击危险程度的 “托里诺分类表”（THE TORINO IMPACT HAZARD SCALE）中第一次有小行星进入“4级”（译注：该分类表最高为10级）。

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This flyby will provide a unique opportunity for researchers to study a near-Earth object up close.

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This asteroid, like the one that will fly by on February 15, is considered a near-Earth object.

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"No Earth impact is possible, " according to Don Yeomans, manager of the Near-Earth Object Program Office at NASA's Jet Propulsion Laboratory.

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