Keeping the Night Sky
On a clear night far from any town, thousands of stars are visible to the naked eye. In a large city, you may be able to count only a few dozen. The reason is light pollution: electric light that shines upward or spills where it isn't needed, making the sky glow.
Light pollution is more than an inconvenience for stargazers. Many birds migrate at night and can become confused by bright buildings, sometimes flying into windows. Sea turtle hatchlings, which use moonlight on the water to find the ocean, may crawl toward streetlights instead. Researchers have also linked bright light at night to poorer sleep in people.
Fortunately, the problem can be fixed. Shields that aim lamps downward, warmer-coloured bulbs and timers that dim lights after midnight all help. Several communities have adopted “dark sky” rules, and many report lower energy bills as a bonus. Protecting the night, it turns out, can be both practical and affordable.