经济学人下载:月球的历史

How do you solve a problem like maria?
如何解决月海这样的问题？

An ancient collision may explain the moon’s Janus faces
一次古老的碰撞可能解释月球的杰纳斯面孔（译者注：杰纳斯是罗马神话中的天门神，头部前后各有一张面孔）

Aug 6th 2011 | from the print edition

EARTH’S moon has a split personality. One half of its surface—the half which, thanks to the vagaries of orbital mechanics, always faces Earth—is dominated by dark, smooth expanses of ancient, frozen lava known as maria (early astronomers, thinking they might be bodies of water, named them after the Latin word for “sea”). The contrast between the darkness of the maria and the brightness of the surrounding highlands forms a pattern popularly known, depending on the culture of the observer, as the man in the moon, the rabbit on the moon or one of many other optical illusions.

地球的卫星---月球有着分裂的人格。其表面的一半---由于轨道力学的变幻莫测，这一半总是面对地球---一直处于黑暗之中。这片黑暗的地方被称为月海，不仅平坦广阔，而且由古老而冻结的火山岩形成（早期的天文学家认为这片地域可能为水体，因而以拉丁词“海”命名）。根据观察者不同的文化，月海的黑暗和周围群山的明亮对比形成了一种众所周知的模式，比如嫦娥，月兔或许多其它视错觉之一。

When astronomers got their first glimpses of the moon’s far side, however, they saw a strikingly different landscape. Early lunar probes revealed a surface that was mountainous, rugged, heavily cratered and virtually devoid of maria. To quote Bill Anders, one of the astronauts on Apollo 8 and thus one of the first three people to see the far side of the moon directly, it “looks like a sand pile my kids have been playing in...all beat up, no definition, just a lot of bumps and holes.”

然而，当天文学家首次瞥见月球较远的那侧时，他们看到了一处截然不同的景观。早期月球探测器显示了这块多山，崎岖不平，拥有大量陨石坑以及几乎毫无大海的地域的表面。引用阿波罗8号宇航员之一，也是首次直接看到月球较远那侧的三个人之一的比尔．安德斯的话说，那块地方“就像孩子们玩的沙堆一样…到处都是破破烂烂的，无法解释，就是很多坑坑洼洼。”