Environment
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.
Run by the National Optical Astronomy Observatory agency, Kitt Peak is one of the largest single collections of astronomical telescopes in the world, a research center where astronomers book to reserve telescope time years in advance. It's also a tourist attraction, where footpaths are marked by signs asking daytime visitors to kindly be quiet as the astronomers catch up on their sleep.
It would seem counterintuitive that Tucson, a city of more than 500,000, would be a dark-sky hallmark. But with the influence of University of Arizona astronomers and the proximity of Kitt Peak, Tucson developed a general civic attention to darker skies, bolstered by local regulations that require outdoor lighting to be shielded to reduce skyward glare.
While Tucson isn't quite attentive enough about light pollution to qualify for inclusion in the IDA's short list of model dark sky places around the world, its soft glow on the horizon from Kitt Peak is less intrusive than the brighter lights of Phoenix imposing into the night sky from 150 miles to the north.
"The biggest concern for Kitt Peak isn't Tucson so much as Phoenix. You can see the glow of Phoenix from almost every professional astronomical observatory in the state of Arizona," said Kardel.
Phoenix, though, can't hold a candle in light pollution to its distant desert neighbor Las Vegas, 300 miles north. A riot of light that stands out even in photos from outer space, Las Vegas is the source of what has been popularly mythologized as the brightest single spot on earth, the Luxor Sky Beam, a blazing column of light blasting into the night sky from the 365-floot-high apex of the pyramid-shaped Luxor Hotel and Casino, itself awash in the conflagration of light that it the Las Vegas Strip at nighttime.
Of course, nobody goes to Las Vegas, or to another blazing nighttime landmark, Times Square, to gaze at the stars. To understand the real effects of excess outdoor lighting on the natural sky, dark-sky advocates have been encouraging people to contemplate light pollution by experiencing its opposite – that is, by visiting places where the skies are dark enough to really see the stars.
The Dark-Sky association has certified a number of locations as dark-sky communities and parks, where natural conditions or local efforts greatly mitigate light pollution. Among them: Natural Bridges National Monument in Utah, Big Bend and Death Valley national parks in Texas and California respectively; Cherry Springs State Park in north-central Pennsylvania and, internationally, Galloway Forest Park in Scotland and Hortobagy National Park in Hungary. A few communities also have received the certified dark-sky distinction, including Flagstaff, Ariz.; the Village of Homer Glenn, Ill.; and the Isle of Sark in the Channel Islands, U.K.
Visiting such places, people might go home and wonder "why do we really need all this unnecessary light in our environment, and can we use light in more intelligent ways that we're doing right now?" said Paul Bogard, author of "The End of Night: Searching For Natural Darkness in an Age of Artificial Light."
To comprehend what has been lost since electric light began filling the night skies, seeing a truly dark sky is an illuminating exercise. Until the advent of electrical lighting in the late 19th Century, observing the celestial phenomena in detail was a routine aspect of life. There are now several generations of people in developed parts of the world who have never seen a truly starry night.
"If you're brought to a dark sky for the first time and see what the Milky Way really looks like, the effect is with you forever," said Bob Parks, the executive director of IDA.
Dark-sky advocates say that pleading strictly through aesthetics is one thing, but that the case becomes stronger when they invoke environmental issues such as saving energy and costs in designing sensible outdoor lighting that reduces light pollution and energy waste.
The energy-efficiency argument augments the ones scientists also employ about the potentially damaging effects, still not fully understood, on animal and plant biology, from sleep disorders in humans to a reduction in nocturnal feeding habitats for birds.
Astronomers in the dark-sky movement have found that the argument just for better stargazing appeals to "a very tiny percentage of the population," said Parks. He said the movement is trying to broaden its appeal by strengthening "the crossover with the environmental movement and global warming."
After all, we generally welcome light at night. "People tend to be afraid of the dark and assume that, well, if no light is bad, then a lot more light is better," said Kardel. "We don't want to push people into darkness and chaos; we want to make sure that there is adequate appropriate light for safe navigation and enjoyment -- but to also remind people basically that lights have an off switch."
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