| Scientists don't know what the early moon looked like. But new images from NASA'S Lunar Reconnaissance Orbiter, published online today in Science, might offer a clue. The spacecraft discovered 14 tiny thrust faults a few kilometers long, the kind of faults that usually appear wherever tectonic plates—or entire planets—compress. Researchers say the faults probably formed less than a billion years ago as the moon contracted and cooled from its fiery beginnings. But the fact that the faults are so small—not nearly as long as the hundred-kilometer ones on, say, Mercury—suggests that the moon hasn't had to cool that much to reach its present state. And that means the early moon probably wasn't a molten glob, as some researchers suspected. Instead, it may have been covered by an ocean of magma around a cooler core. |
科学家们不知道早期的月球是什么样子。美国航空航天管理局的“月球侦察轨道卫星”所拍下的新图像可能为此提供了线索。这些图像发表在今天的《科学》杂志在线版上。这架太空船发现了14道几公里长的逆冲断层，这种断层通常出现在构造板块或整个行星受到压缩的地方。研究人员称，这些断层很可能形成于不到十亿年前，当时月球处于炽热的初始阶段之后开始冷却收缩的时期。然而，这些断层如此之小，远远不比水星上一百公里长的断层，该事实说明月球不必冷却太多就可以达到目前的状况。这还意味着，很可能早期的月球并不是一个熔化的团状物体，它当时可能被岩浆的海洋所覆盖，而内部是一个温度较低的核心——正像一些研究人员所认为的那样。 |
