Unit 2 Task 3

We usually think of pollution as a harmful waste substance that threatens the air and water. But some people have become concerned about another kind of pollution. It can be everywhere, depending on the time of day. And it was not thought of as a substance. It is light.
    The idea of light pollution has developed with the increase of lights in cities. In many areas, this light makes it difficult or impossible to observe stars and in the night sky. In 1998, the International Dark-Sky Association formed. This organization wants to reduce light pollution in the night sky. It also urges the effective use of electric lighting.
　　There are a number of reasons why light pollution is important. One has become clear at the Mount Wilson near Los Angeles, California. Mount Wilson Observatory was home to the largest telescopes in the world during the first half of 1900.

During that period, Los Angeles grew to become one of America's biggest cities.

Today, light from Los Angeles makes the night sky above Mount Wilson very bright. It is no longer an important research center because of light pollution.

Light pollution threatens to reduce the scientific value of research telescopes in other important observatories. They include Lick Observatory near San Jose, California and Yerkes Observatory near Chicago, Illinois.
　　Light pollution is the result of wasted energy. Bright light shining into the sky is not being used to provide light where it is needed on Earth. Poorly designed lighting causes a great deal of light pollution. Lights that are brighter than necessary also cause light pollution.
　　Recently, two Italian astronomers and an American environmental scientist created a world map of the night sky. The map shows that North America, Western Europe and Japan have the greatest amount of light pollution.

Most people in America are surprised to find out that they are able to see our own galaxy, the Milky Way, with their own eyes. But about three fourths of Americans cannot see the Milky Way because of man-made light.
　　Objects in the night sky are resources that provide everyone with wonder. And light pollution threatens to prevent those wonderful sights from being seen.