New York Times: As cities grow, so does the amount of light emitted at night. As a result, it is becoming increasingly difficult to see the stars. A movement to minimize artificial lighting is spreading globally, with groups such as the International Dark-Sky Association, headquartered in Tucson, Arizona, working “to preserve and protect the nighttime environment and our heritage of dark skies through environmentally responsible outdoor lighting.” Dimming streetlights, aiming them toward the ground, and installing motion sensors are among some of the ways that cities are making their skies darker. For even better night-sky viewing, dark-sky parks are being designated around the world. Besides the aesthetic benefits of cutting light pollution are the economic benefits: Reducing the number and brightness of lights saves energy and, ultimately, money. And unlike many environmental problems, light pollution is reversible. It is “not destroying the nighttime sky. We can recover it,” says Cheryl English, a vice president at lighting company Acuity Brands and a member of the International Dark-Sky Association.