They combine with dust particles from the comet to form a huge cloud.

它们与来自彗星的尘埃颗粒结合在一起，形成了巨大的云团。

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As the comet gets even nearer to the sun, a solo wind blows the cloud behind the comet, thus forming its tail.

当彗星更接近太阳时，一股单独的风将云朵吹到彗星后面，它的尾巴就是这样形成的。

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Every so often a comet gets flung out of the Oort Cloud, a swarm of comets on the fringes of the solar system, and gets close enough to Earth for us to see it.

经常有彗星被甩出奥尔特云(在太阳系边缘的彗星群)，并靠近地球到肉眼可以观测的距离。

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Stardust passed through a cloud of material surrounding comet Wild Two in January of two thousand four.

VOA: special.2009.09.30

Only when a comet arriving from the Oort cloud has its orbit tweaked by a close encounter with a planet does it settle into a more regular existence.

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Cheng says the comet is likely making its first visit to the inner solar system from the Oort cloud, a reservoir of hundreds of millions of comets encircling our solar system at a distance of about a light year.

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