英语听力：探索发现 2014-05-23 BBC 地平线：陨石的真相-6

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Long before the meteorite² reached its explosivefinale in full view of Chelyabinsk’s dash cams, it had a very differentexistence and going by a very different name. 

 

Meteorites begin life in deep space as part of muchlarger bodies called asteroids⁵. These can range in size from just a few metresto more than 900 kilometres, the leftovers⁶ from the nebula⁷ that created oursolar system some 4.6 billion years ago. And millions of them circle the Sun ina trail known as the asteroid⁴ belt. Here, collisions create smaller fragmentsand when these fall towards Earth, they take on one of two forms. The smallestpieces will burn up in the atmosphere to become meteors, what we call shootingstars. Only the largest fragments that make it all the way to the Earth’ssurface are called meteorites. 

 

The meteorite is a piece of rock from space or apiece of metal from space that falls through our atmosphere and actually hitsthe ground to be recovered. And technically⁸, scientists love their words, it’snot a meteorite before it’s actually found and discovered.  

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