TOHONO O'ODHAM RESERVATION, Ariz. – One night a few weeks ago, the telescopes reached into the sky at the Kitt Peak National Observatory, scanning for the stars from a mountain peak in the Sonaran Desert of southern Arizona. But the celestial sparks were hard to see, their luminosity blotted out by the blue moon of Aug. 21.

But at least that was natural light. The moon, after all, wanes with hours and days, so before long the 24 giant optical telescopes 6,875 feet high on the peak were shrouded again in nocturnal darkness, returning the night to the astronomers, for whom light pollution from manmade sources is a growing nemesis worldwide.

The Kitt Peak location was leased by the federal government from the Tohono O'Odham tribe in the late 1950s because the night skies here are usually clear and dark, even though it's little more than 50 miles southwest from the glow of Tucson. Today, for scientists and tourists alike, it a good spot to contemplate the deleterious effect that artificial lighting has on humankind's relationship with the night sky – and, also, the possibility for change.

"Part of the reason the telescopes on Kitt Peak are enormously productive is that the sky there is staying relatively dark," said Scott Kardel, an astronomer who is managing director of the International Dark-Sky Association (IDA), a group of professional and amateur astronomers, aligned with a growing number of civic and business supporters, who promote the idea that light pollution can be controlled and even greatly reduced, once people understand the scientific, aesthetic, environmental and even health benefits of darker skies.

Until electrical lighting began to artificially brighten our nights just over a century ago, a sky brimming with stars, he said, "was something that our ancestors had for all of human history -- a night that sky inspired science, art, religion, philosophy."

Excessive light pollution is more than just a curse to astronomy and aesthetics, dark-sky proponents say. The long-term effects of light pollution "may have serious physiological consequences for humans, ecological and evolutionary implications for animal and plant populations, and may reshape entire ecosystems," according to a 2010 report on light pollution entitled "The Dark Side of Night," in the journal Ecology and Society.