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。
2
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。
3
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.