So to talk about where meteorites come from, we need to talk about comets and asteroids.

那么讲到流星体从何而来，我们就需要讨论下彗星和小行星。

youdao

I'm not going to go into any depth on comets and asteroids now, but we'll come back later and do that.

我现在不打算深入讨论彗星和小行星了，但是我们稍后会再回到这个点上，讨论这方面的内容。

youdao

This cannot be correct unless Unoosa considers aliens to be near-earth objects (like comets and asteroids).

如果外太空司把近地天体(如彗星和小行星)当成“近地物体”的话，那么这个说法才可以说得通。

youdao

Both comets and asteroids have hit Earth in the past.

CNN: While you were working: An asteroid just flew by

Data from NEAR could help answer questions about the origin and composition of asteroids, comets and the solar system, according to the mission managers at the Applied Physics Laboratory in Laurel, Maryland.

CNN: NEAR and Eros

"The guess is that both the water and the dark material, which we think is organic-rich material, were delivered by the same objects impacting Mercury: some mixture of comets and the kinds of asteroids that are rich in organic and volatile material like water ice, " Prof Solomon said.

BBC: Mercury's water ice at north pole finally proven