有一种说法是，它们来自于数亿年前撞击月球的慧星和小行星，后来转移到了极点。

One theory is that they came from comets and asteroids, which pounded the lunar surface billions of years ago, and later drifted to the poles.

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1994年7月，慧星“皮鞋匠”——利维撞击了木星。

In July 1994, the Comet Shoemaker -levy collided with Jupiter.

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