nonu @ 2007.12.25 , 12:12
月球是由地球碎片形成的？
长久以来科学家们一直坚信月球是由火星那么大的行星和地球碰撞产生的，但根据最近对月球岩石的测试，证明月球可能是在地球形成之后被一个巨大的小行星撞击而形成。
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The moon was formed from fragments of Earth after a collision with a giant asteroid relatively late in our planet's formation, new tests of moon rocks show.
根据最近对月球岩石的测试，证明月球可能是在地球形成之后被一个巨大的小行星撞击形成的。
The finding upends many of the prior theories for how the moon came to be, researchers say.
研究人员说已经找到很多支持这个月球形成理论的依据。
Scientists have long believed that the moon was formed by a collision between our planet and a Mars-size object.
长久以来科学家们一直坚信月球是由火星那么大的行星和地球碰撞产生的。
Computer models have shown that in this scenario 80 percent of the moon's material should have come from the asteroid, with only 20 percent from Earth.
相应的计算机模型显示月球物质成分中80%来自小行星，只有20%来自地球。
But the new study of moon rocks collected three decades ago by Apollo astronauts, however, found that Earth and the rocks were too similar for that to be the case.
但最近对阿波罗卫星三十年前收集的月球岩石进行研究，发现其成分与地球物质十分相似。
The most likely explanation is that the moon was formed primarily of Earthly material, the authors say.
所以最有可能的理由是：月球是由大撞击之后的地球碎片形成的。
Lead author Mathieu Touboul of the Swiss Federal Institute of Technology in Zurich said there is another theory that may explain its formation.
瑞士苏黎士技术学院研究员 Mathieu Touboul 说，它特别的物质成分另有解释。
"Alternatively, the material from which the moon eventually formed was a magma disk, connected to the Earth by a common atmosphere," he said in a statement.
月球岩石成分是岩浆岩，很可能是因为当时月球上有跟地球是共有的大气环境(# nonu：这样说来，月球上的环形山都是当初的火山？真有点像哎)。
Material from Earth and the nascent moon could then be exchanged via a shared metal-vapor atmosphere.
而且地球和初期月球上的物质可能通过共有的大气层得以交换。
By the time the two worlds had settled back down and begun drifting apart, their compositions would have been virtually identical.
到地球和月球分离的时候，它们的物质成分已经差不多了。
"New simulations of such a process have recently shown that such exchange is possible," Touboul said.
“新的模拟实验证明我们猜想的这个物质交换过程是可能的”，Touboul 说。