英语听力：探索发现 2014-05-25 BBC 地平线：陨石的真相-7

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Few places in the world have got as many meteoritesas the Natural History Museum, meteorites like this. It’s a cracker³, isn’t it? Theones that are out here on display are just a fraction. The bulk of thecollection is behind the scenes and that is where the science goes on. 

 

So all these are meteorites in some shape or form? 

 

They are all either meteorites or…

 

Professor Sara Russell is expert at decoding⁴ themessages hidden within these fragments of space rock.

 

This looks quite rocky, what about that one?

 

It looks like a humble⁵ rock but if you hold it—be verycareful of this one, this is older than the Earth. It is the oldest thing youwill ever hold. 

 

This is older than what, 4.6 billion years?

 

Yes. We have this number of 4.6 billion years of theage of the solar system. We know that from meteorites like this one and from lookingat the age of the components⁶ within it. So if you can see, it’s got theserounded objects in it, which are 1mm to 1cm in size. These are calledchondrules and these were once free-floating. Before there were planets, thesewere free-floating in the solar system around the very young Sun and then theyslowly coalesced⁷ to make asteroids⁸ and larger and larger objects untileventually planets were formed. These are the building blocks of planets.

 

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