*National Geographic* (Nov. 2008 issue) has a compelling cover story on “The End of Night,” which explains how excessive artificial lighting is damaging our planet. The article describes the enormous harm to wildlife caused by lights that disturb normal nocturnal cycles. In tragic terms, we learn about migrating birds crashing into lit-up skyscrapers, sea turtles struggling to find dark beaches on which to nest, and hatchlings that are suddenly vulnerable to predators.
Casualties to wildlife are only part of the costs of unnecessary lighting at night. A growing number of humans can no longer see stars, or what they can see represent a tiny fraction of what the night sky has to offer. This map gives a picture of light intensity at night around the world.
I became more aware of what I was missing when I took my daughter to Yosemite National Park in 2003. On a chilly August night, we stood on Glacier Point during a period when Mars was making its closest pass to Earth in 60,000 years. The Milky Way was so vivid, we felt like we could touch it. Millions of stars were visible in every direction. Thanks to a generous astronomer, who let us peer into his telescope, we saw more planets, including Saturn, Neptune, and Uranus. That night was a powerful, truly spiritual experience.
As National Geographic points out, more efficient and targeted outdoor light fixtures can help address a considerable portion of the night lighting problem. In fact, many cities and towns now have laws that restrict the use and type of lights at night. Reducing unnecessary lighting has other welcome benefits: lower energy costs and less greenhouse gas emissions.
**Update:** The New York Times had an encouraging article this past Sunday on efforts to reduce night lighting in New York City (watch the short video embedded in the Times story). In addition, the International Dark-Sky Association has a directory of outdoor light fixtures that meet the organization’s standards for avoiding unnecessary light pollution.