Light pollution is caused by excess light that is beamed into the sky. The extra light shines from houses, office buildings, streetlights, and sports fields. It reflects onto low clouds, causing a sky glow that blots out the stars.
Bad light fixtures cause much of the problem. Most of the murky glow in the night sky is wasted light, according to David Crawford. He is the director of the International Dark-Sky Association, an organization that is working to stop light pollution. Crawford says that lights should point at the ground, not at the sky.
About one-third of all lighting in the United States is wasted. Wasted light costs billions of dollars per year. It also harms the environment.
Electricity comes from power plants. Half of the country’s power plants burn coal, which pollutes the air. The power plants release sulfur dioxide and carbon dioxide. Sulfur dioxide creates harmful acid rain. Carbon dioxide traps heat near the Earth’s surface, causing global warming.