水手号宇宙飞船发现火星表面，还有它的两个卫星表面，都有由太空坠落的流星体造成的陨石坑。

The Mariner spacecraft found that the surface of Mars, as well as that of its two moons, is pitted with impact craters formed by meteoroids falling in from space.

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他们计算出这种星体的数量是我们“主星序星体”的两倍。我们的太阳就属于“主星序星体”，现在仍然通过燃烧氢燃料发光。

They calculated that they could be almost twice as common as "main-sequence stars" - such as our own Sun - which are still burning through their hydrogen fuel stock.

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落入地球的两个宇宙物体同属于一个双星体系的几率是很小的，如果有，它们应该是同时撞击了地球。

The odds of the two rocks being part of a binary system is small -- if they were, they should have hit simultaneously.

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