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 ISO stars.
If you’ve
ever driven toward a big city at night and seen its glow from a great distance,
you’ve witnessed fight 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. |
