英语听力：探索发现 2014-05-30 BBC 地平线：陨石的真相-9

 It’sremarkable how we are able to build up this picture of what’s going on millionsof miles away in the solar system. It’s one of the joys of science really, justalmost like a detective picking up on those tiny clues to tell a bigger story. Sothat the big question, the one that really needs answering, is why do some ofthese asteroids² suddenly head straight towards us? 

 

Over95% of asteroids are found in an orbit between Jupiter and Mars called the mainbelt. It’s almost 200 million kilometres across and home to millions of theseorbiting rocks. And these asteroids have been following the same path formillions of years. So long as they remain here, they pose no threat to Earth. Butoccasionally, one goes astray. 

 

Collisionsare one of the reasons why this might happen. But in the last decade, we’velearned that just a few rays of light are enough because one scientist hastracked the orbit of just one of these millions of rocks. 

 

SteveChesley of NASA’s Jet Propulsion Lab in California has made a study of a 200million-ton asteroid¹ called Golevka. 

 

Thisis a model of Golevka. It’s actually about 500 metres across, say the size of afootball stadium. It rotates in this direction. As you can see, it has a veryangular shape to it.

1 asteroid   

n.小行星；海盘车(动物)

参考例句：

• Astronomers have yet to witness an asteroid impact with another planet.天文学家还没有目击过小行星撞击其它行星。
• It's very unlikely that an asteroid will crash into Earth but the danger exists.小行星撞地球的可能性很小，但这样的危险还是存在的。

2 asteroids   

n.小行星( asteroid的名词复数 )；海盘车，海星

参考例句：

• Asteroids,also known as "minor planets",are numerous in the outer space. 小行星，亦称为“小型行星”，在外太空中不计其数。
• Most stars probably have their quota of planets, meteorids, comets, and asteroids. 多数恒星也许还拥有若干行星、流星、彗星和小行星。