고등학교 공통영어1 (미래엔 김성연) 연계 글

On a clear night in a big city, you may see only a few stars, with streetlights and bright windows glowing all around you. Scientists call this light pollution: artificial light that is brighter than needed or that shines where and when it is not needed. It affects not only our view of the stars but also the lives of birds, insects, and people.

The problem is spreading. A world atlas published in 2016 showed that more than 80 percent of the world's people live under light-polluted skies. A study published in 2023 used more than 50,000 reports from volunteers who had recorded how many stars they could see. The reports showed that between 2011 and 2022, the night sky grew brighter by 7 to 10 percent each year. Yet much of this extra light serves no purpose. Experts in the United States estimate that 30 to 35 percent of outdoor light is wasted, mostly because lamps are unshielded, poorly aimed, or too bright.

Wildlife suffers, too. Many birds migrate at night, and bright city lights can draw them far off their routes. Lit windows not only attract these birds but also lead some of them to crash into the glass. Moths and other flying insects gather around streetlights, with many of them circling the lamps instead of searching for food. They are drawn most strongly to light that is rich in blue, like that of many white LED lamps. Researchers also believe that light at night can disturb people's sleep by lowering melatonin, a hormone that helps control sleep.

Unlike many other kinds of pollution, however, light pollution can be reversed quickly. The first step is to use shielded lamps, which brighten the street with all of their light pointed at the ground. Not only does such a lamp keep the sky darker, but it also wastes less energy. Experts also recommend using no more light than a place needs. They advise using warm, yellowish light with a color temperature of 3,000 kelvins or lower, since such light contains far less blue. Finally, lights should be off when no one needs them; timers and motion sensors can turn them off automatically.

If more towns take these steps, people may someday walk under streetlights with their light aimed at the sidewalk and still see the stars.