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  3. Light Night, Dark Stars Thousands of people around the globe step outside to gaze at their night sky. On a clear night, with

Light Night, Dark Stars Thousands of people around the globe step outside to gaze at their night sky. On a clear night, with

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问题                     Light Night, Dark Stars
    Thousands of people around the globe step outside to gaze at their night sky. On a clear night, with no clouds, moonlight, or artificial lights to block the view, people can see more than 14, 000 stars in the sky, says Dennis Ward, an astronomer with the University Corporation for Atmospheric Research(UCAR)in Boulder, Colo. But when people are surrounded by city lights, he says, they’re lucky to see 150 stars.
    If you’ve ever driven toward a big city at night and seen its glow from a great distance, you’ve witnessed light pollution. It occurs when light from streetlights, office buildings, signs, and other sources streams into space and illuminates the night sky. This haze of light makes many stars invisible to people on Earth. Even at night, big cities like New York glow from light pollution, making stargazing difficult.
    Dust and particles of pollution from factories and industries worsen the effects of light pollution. "If one city has a lot more light pollution than another, " Ward says, "that city will suffer the effects of light pollution on a much greater scale. "
    Hazy skies also make it far more difficult for astronomers to do their jobs.
    Cities are getting larger. Suburbs are growing in once dark, rural areas. Light from all this new development is increasingly obscuring the faint light given off by distant stars. And if scientists can’t locate these objects, they can’t learn more about them.
    Light pollution doesn’t only affect star visibility. It can harm wildlife too. It’s clear that artificial light can attract animals, making them go off course. There’s increasing evidence, for example, that migrating birds use sunsets and sunrises to help find their way, says Sydney Gauthreaux Jr. , a scientist at Clemson University in South Carolina. "When light occurs at night, " he says, "it has a very disruptive influence. " Sometimes birds fly into lighted towers, high-rises, and cables from radio and television towers. Experts estimate that millions of birds die this way every year.
Why does the writer think growing cities affect astronomers’ work?
选项 A、Because the once dark rural areas are polluted by lights.
B、Because they can still see stars in rural areas.
C、Because rural areas are not a good place for astronomers to study stars.
D、Because faint light given off by stars can still be seen on a clear night.
答案A
解析 题意：为什么作者认为城市规模的扩大会影响天文学家们的工作?答案在第五段中可以找到。随着城市规模的扩大，曾经昏暗的乡村逐渐变成了市郊，那里的灯火使科学家无法观测到星体发出的微弱光芒，故本题选A。
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