Until the 2009 collision, the last known impact event on Jupiter was the famous "death" of Comet Shoemaker-Levy 9 in 1994.

2009年的碰撞之前，上一次已知的碰撞木星事件是著名的1994年苏梅克·列维9号彗星的死亡碰撞。

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That’s been observed twice before, when comet Shoemaker-Levy 9 crashed into Jupiter in July 1994, and when a large asteroid smacked the planet last summer.

这种黑羽碎片的现象已经观察到了两次了，一次是苏梅克-列维9彗星于1994年7月撞向木星，另一次是去年夏天一个比较大的小行星于撞击了这个行星。

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One answer might be that the two impacts were, in effect, simultaneous that the objects which created Shiva and Chicxulub were the daughters of a comet that had broken up in space and hit the Earth a few hours apart, as the pieces of comet Shoemaker-Levy 9 hit Jupiter in 1994.

ECONOMIST: Mass extinctions