托福阅读机经背景材料：英仙座流星雨

　　Sky-watchers could be in for "fantastic views" over the next two days as the Perseid meteor shower reaches its peak.

　　According to Nasa, the shower could produce a display of up to 80 meteors per hour.

　　"A waxing crescent moon will set before the shower becomes active, setting a perfect stage for meteor watching," said the US space agency on its website.

　　Experts are urging people to head away from city lights for the best views.

　　John Mason from the British Astronomical Association (BAA) told BBC News: "Weather-permitting, we should be in for a very good show across the UK.

　　"The shower has been ongoing for a week now and we have already seen some very bright meteors whizzing overhead."

　　The Perseid meteor shower is caused by debris from the comet Swift-Tuttle.

　　Every 133 years, the huge comet swings through the inner part of our Solar System and leaves behind a trail of dust and gravel.

　　When Earth passes through the debris, specks hit our atmosphere at 140,000mph and disintegrate in flashes of light.

　　The Royal Astronomical Society (RAS) said the relatively warm summer nights would make this meteor shower one of the more comfortable to watch.

　　* The meteors are called the Perseids because they appear to fly out of the constellation Perseus

　　* The yellow dot marks the Perseid radiant. The meteors can appear in any part of the sky, but all of their tails will point back to there

　　* The best views of the meteor shower are likely to be in the Northern Hemisphere