The dark-sky movement is a collection of worldwide efforts aimed at minimizing the impact of artificial light at night. No single organization heads it.
“It’s an effort to think in terms of light that’s really needed,” says Scott Kardel, managing director of International Dark-Skies Association (IDA), a Tucson, Arizona-based organization founded in 1988 to promote the thoughtful use of light at night.
According to the association, two-thirds of the world’s population lives where they cannot adequately view a starry sky due to excessive, misdirected or obtrusive artificial light. Such “light pollution” is outpacing population growth by 4 percent as developing nations embrace electricity. And in the United States, unnecessary lighting at night wastes an estimated $2.2 billion annually.
Still, the world is only beginning to understand the effects on its people, planet and resources.
In 2012, the American Medical Association reported that widespread use of artificial light causes a constant disruption of circadian biological rhythms on the average American. Studies have found correlations between circadian disruptions and increases in breast cancer, mood disorders, diabetes and obesity.
Excessive artificial light at night also puts wildlife at risk. The natural length of night regulates animals’ migration, mating, sleeping and food foraging patterns. Several studies have proven the harmful effects of artificial lights at night on sea turtles, bats and songbirds. In North America alone, more than 100 million birds die annually in collisions with lighted towers and buildings.
“People aren’t just concerned about the night sky and energy use, but also about its effects on human health and the environment,” Kardel says.
Concerted efforts to minimize excessive light at night began during the early 1970s, spearheaded by amateur astronomy clubs.
“In the 1960s, most people could just set up a telescope in their backyards,” says Sean O’Brien, astronomer with the Albert Einstein Planetarium in Washington, D.C. “But by the ’70s, because of light pollution, amateur astronomers now had to travel from their homes in the suburbs in order to obtain quality night skies.”
Governmental bodies began listening to the concerns of stargazers. “Tucson passed one of the nation’s first lighting ordinances in 1972, and since then thousands of cities have followed,” Kardel says. Nineteen states have joined in the movement by passing laws related to the use of lighting.