Elearning
Light Pollution is a threat to Wildlife, Safety and the Starry Sky
A
After hours of driving south in the pitch-black darkness of the Nevada desert, a dome of hazy gold suddenly appears on the horizon. Soon, a road sign confirms the obvious: Las Vegas 30 miles. Looking skyward, you notice that the Big Dipper is harder to find than it was an hour ago.
B
Light pollution—the artificial light that illuminates more than its intended target area—has become a problem of increasing concern across the country over the past 15 years. In the suburbs, where over-lit shopping mall parking lots are the norm, only 200 of the Milky Way’s 2,500 stars are visible on a clear night. Even fewer can be seen from large cities. In almost every town, big and small, street lights beam just as much light up and out as they do down, illuminating much more than just the street. Almost 50 percent of the light emanating from street lamps misses its intended target, and billboards, shopping centers, private homes and skyscrapers are similarly over-illuminated.
C
America has become so bright that in a satellite image of the United States at night, the outline of the country is visible from its lights alone. The major cities are all there, in bright clusters: New York, Boston, Miami, Houston, Los Angeles, Seattle, Chicago—and, of course, Las Vegas. Mark Adams, superintendent of the McDonald Observatory in west Texas, says that the very fact that city lights are visible from on high is proof of their wastefulness. “When you’re up in an airplane, all that light you see on the ground from the city is wasted. It’s going up into the night sky. That’s why you can see it.”
D
But don’t we need all those lights to ensure our safety? The answer from light engineers, light pollution control advocates and astronomers is an emphatic “no.” Elizabeth Alvarez of the International Dark Sky Association (IDA), a nonprofit organization in Tucson, Arizona, says that overly bright security lights can actually
A
After hours of driving south in the pitch-black darkness of the Nevada desert, a dome of hazy gold suddenly appears on the horizon. Soon, a road sign confirms the obvious: Las Vegas 30 miles. Looking skyward, you notice that the Big Dipper is harder to find than it was an hour ago.
B
Light pollution—the artificial light that illuminates more than its intended target area—has become a problem of increasing concern across the country over the past 15 years. In the suburbs, where over-lit shopping mall parking lots are the norm, only 200 of the Milky Way’s 2,500 stars are visible on a clear night. Even fewer can be seen from large cities. In almost every town, big and small, street lights beam just as much light up and out as they do down, illuminating much more than just the street. Almost 50 percent of the light emanating from street lamps misses its intended target, and billboards, shopping centers, private homes and skyscrapers are similarly over-illuminated.
C
America has become so bright that in a satellite image of the United States at night, the outline of the country is visible from its lights alone. The major cities are all there, in bright clusters: New York, Boston, Miami, Houston, Los Angeles, Seattle, Chicago—and, of course, Las Vegas. Mark Adams, superintendent of the McDonald Observatory in west Texas, says that the very fact that city lights are visible from on high is proof of their wastefulness. “When you’re up in an airplane, all that light you see on the ground from the city is wasted. It’s going up into the night sky. That’s why you can see it.”
D
But don’t we need all those lights to ensure our safety? The answer from light engineers, light pollution control advocates and astronomers is an emphatic “no.” Elizabeth Alvarez of the International Dark Sky Association (IDA), a nonprofit organization in Tucson, Arizona, says that overly bright security lights can actually