英语听力：探索发现 2014-06-04 BBC 地平线：陨石的真相-10
时间：2014-08-26 08:53:46
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（单词翻译）
Heset out to investigate a hundred-year-old theory that said asteroids2 werepowered by the Sun itself. It was called the Yarkovsky effect. The Yarkovskyeffect is a very small acceleration3 and acts on asteroids and what it is is ifyou take a model, the Sun is hitting the asteroid1, warming the surface. And asthe asteroid rotates, that hot surface radiates the heat out in a differentdirection into space and that causes an acceleration, a very slightacceleration coming from the photons that were emitted from the asteroid. The ideais that this acceleration, slight as it is, can have significant effects uponthe orbits of asteroids over millions of years.
Itwas an
intriguing4 idea. What sent asteroids out of their orbit and on a pathtowards Earth was photon propulsion. But what was lacking was proof.
TheArecibo telescope is over 300 metres in diameter. It’s one of the most powerfultelescopes in the world and it uses
radar5 to mark the precise position ofobjects in deep space. It was this telescope that would allow Steve Chesley todetect any tiny
alterations6 in the orbit of asteroid Golevka more than 15million kilometres out in space.
Weknew that it would be in one place if the Yarkovsky effect wasn’t
acting7 on it,and it would be over here if it was acting and our models were correct.
WhenSteve and his team studied the data, the results were unequivocal.
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