Gaze up at the night sky and see dazzling stars and planets, arrayed like cosmic diamonds on a black velvet drop cloth. Or maybe not.

Increasingly, the view above is being blocked by glare from overly bright billboards, harshly lighted parking lots and shopping malls and gas stations that stay lighted all night. Across the nation, poor or inefficient lighting is wiping out a precious resource—the sky at night.

"It’s gotten to the point where the vast majority of people who live within urban areas can only see the brightest stars," says Chris Luginbuhl, an astronomer at the U.S. Naval Observatory in Flagstaff, Ariz. Astronomers have groused for years that brightly lighted skies destroy the ability to see into the heavens . But now, a growing number of cities and states are trying to reclaim the night, too. Increasingly, they’re interested in preserving energy efficiency as well as good sky-watching.

Legislatures in New Mexico and New Hampshire are considering shutting off lights at ballparks and recreational areas after 11 p.m. Texas, Michigan, Massachusetts and Wyoming are debating statewide crackdowns on outdoor lights that cast their beams up, rather than down.

Atlanta passed a law in December banning billboards that are lighted from below and shed light into the sky. Los Angeles is changing 234,000 street lights so light shines no higher than the bulbs. Over the past five years, at least 150 cities and counties in states from Virginia to Hawaii have put laws on the books against nighttime glare.

Two states—Arizona and Maine— already have statewide laws regulating everything from the intensity of outdoor lighting to the length of time those lights can burn All could help save what the International Dark-Sky Association estimates is $2 billion wasted every year by Americans on light that flows upward, rather than downward, where it’s needed.

"It’s become a pocketbook issue now," noted astronomer David Levy says. "We’re wasting all this money to light the underbellies of birds and airplanes."

Levy has briefed Vice President Gore and others on the problem, but it’s not an easy sell. "A lot of people still have the feeling that brighter is better," Levy says. The move to "take back the night" dates to 1958, when Flagstaff became the world’s first city to fight encroaching light. It banned the use of searchlights for advertising purposes in deference to the area’s two prominent astronomical centers: the Lowell Observatory and U.S. Naval Observatory.

But it wasn’t until this decade that other cities got serious about sky glow, also known as "light pollution." "It’s not pollution in the classic sense. It’s not toxic. But it does have a toxic component because it causes energy at the utility to be used more excessively," says Clark Reed, an atmospheric pollution manager with the Environmental Protection Agency.

The EPA has no congressional mandate to monitor light pollution, but it does encourage cities and industries to adopt more efficient lighting. "As our population continues to grow, suburbia and cities will expand. Light pollution, if not addressed, will only get worse," Reed says.

The United States is not alone in its quest for darker night skies. Australia has passed a law to stop outdoor lights at homes and businesses from spreading their beams in all directions. Proponents of dark skies are pushing for similar legislation in Japan, France, Greece, Italy and Germany.

In Toronto, Canada, skyscraper managers are urged to turn off lights at night to keep migratory birds from colliding with buildings. Each year, about 10,000 birds are killed or injured when they become disoriented and either smash into buildings or circle lights until they fall from exhaustion.

In the Mediterranean, as in parts of coastal Florida, scientists are worried that glaring beach lights from homes and businesses cause young turtles hatched in the sand to lose their way to the sea. Attracted by the light, the turtles wind up stranded on shore where they starve to death.

The International Astronomical Union, with 8,300 individual members and 60 member countries, plans to debate the problem of light pollution at a meeting in Vienna, Austria, in July. The union will present its recommendations a week later to the U.N. Committee for the Peaceful Uses of Outer Space.

Beyond the economic and ecological arguments for preserving the night sky lie sound psychological reasons , says David Crawford, a retired astronomer in Tucson, Ariz., and head of the International Dark-Sky Association. "Mankind and everything on the Earth have grown up with day-night cycles," Crawford says. "As we remove the night and turn it into day, it’s a psychological stress on our system. The future will show that as we bring back the night, there’s a calming influence on people."