Copyright © 2001 Tucson Citizen
Light pollution in Tucson
The city's increasing glow threatens the work of top astronomers and, some say, can rob us of a spiritual and cultural boost.
A satellite image of North America from the World Atlas of the Artificial Night Sky Brightness indicates the areas of the highest levels of light pollution in yellow, red and white (highest). Inset shows Arizona and the surrounding region.BOTTOM RIGHT: Astronomer John Glaspey, with the 2.1-meter telescope at the Kitt Peak National Observatory.
MARI N. JENSEN
Driving from Tucson to Phoenix at night used to mean leaving the bright lights of the big city behind and slipping into the velvety darkness of a star-filled desert night.
Not any more.
A trip north on Interstate 10 now is punctuated continually by the glow of civilization.
Tucson's lights blend into those of Marana, followed by those of the truck stops at Picacho, Eloy and Toltec, which herald the approach of Casa Grande.
And as that city's glimmer recedes in the rearview mirror, the 24-hour glow of Arizona's largest metropolitan area lies dead ahead.
Lights bleach out the night sky. Stars are hard, if not impossible, to see.
The reason is more easily apparent: More people mean more lights.
For most people, the star-filled heavens that awed our ancient predecessors and inspired poets are a thing of the past.
One out of 5 of the world's people lives where nighttime lighting makes it impossible to see the Milky Way with the naked eye, an international team of astronomers reported recently.
Astronomer John Glaspey, who researches the universe from Kitt Peak National Observatory, has noticed a change in the night sky since he got his doctorate at the University of Arizona in 1971.
When he was a teaching assistant at UA, he took his classes to the roof of Steward Observatory on the campus to see the constellations.
"I bet you couldn't do that now," because of all the light pollution in midtown Tucson, he said.
Although Tucson and Pima County's outdoor light codes have held down light pollution, Glaspey said the region's night sky is getting brighter as the population grows.
He and other local astronomers are concerned that increased glow from Tucson and the surrounding regions will make the telescopes on Kitt Peak and Mount Hopkins less valuable for viewing the sky's faintest objects, such as distant galaxies.
"Kitt Peak has been here 40 years now. It was located near Tucson because it provided access to a major university and a reasonable metropolitan area," he said, adding, "Then, it was very dark."
"But now, 40 years later, Tucson has grown and continues to grow. We're concerned about light pollution."
Although the Tucson metropolitan area has been a leader in enacting outdoor lighting codes that keep nighttime skies dark, the sky directly overhead has brightened 15 percent to 20 percent in the past decade, according to measurements that astronomers have taken at Kitt Peak and at the Whipple Observatory on Mount Hopkins.
Richard Green, director of Kitt Peak National Observatory, said that in the same period, the region's population went up 40 percent.
"So that shows that the city and the county ordinances and people's compliance with them actually help maintain a relatively dark sky," he said.
But as the population grows and more light ends up in the nighttime sky, it will be harder for astronomers at Kitt Peak and Whipple Observatory to detect the oh-so-faint beams of light from distant celestial objects.
"It's like I'm looking for the glitter of a little pen-ray flashlight in the glare of bright sunlight," Green said. "That 20 percent increase in sky brightness means it takes us 40 percent longer to record the same faint, distant objects. You get less done per expensive hour of operating the telescope."
He said it costs about $6,000 per night to run the 4-meter telescope, the biggest on Kitt Peak.
Craig Foltz, director of the MMT telescope at Whipple Observatory, agreed with Green.
He said Tucson's outdoor lighting code has "really been wonderful. It has continued to let major observatories operate near a city that has seen dramatic growth."
CONTRASTS IN LIGHTING:
At the Chevron station on the corner of Grant Road and Stone Avenue (below), harsh lighting punctuated by the hot spots of exposed bulbs is so much brighter and glaring than the surrounding area that it can bother the eyes of people driving by. In contrast, the Chevron station at Grant Road and Tucson Boulevard (above) has more-uniform, dimmer lighting that minimizes glare while providing plenty of light for pumping gas.
But the increase in light pollution that comes with growth "is a real threat" to local observatories, he said.
"There are observatories that have been compromised by light pollution," he said, citing historically significant observatories in California such as the Mount Wilson Observatory and the Lick Observatory.
"What's happened is, the University of California has taken its interest and moved it to Mauna Kea (in Hawaii)," he said. "The University of Arizona is moving its interest to Mount Graham."
Foltz himself was inspired to study astrophysics when he went to a rural college after growing up outside New York City.
"I had this epiphany - 'Oh, my god, that's what they talk about! That's the Milky Way!' "
He can't see the Milky Way from his midtown home near Broadway and Alvernon Way.
Although he thinks the darkness of the skies around Tucson is "as good as it could be," he said, "But it would be better for my spirit if our sky were darker."
The night sky has certainly been a spiritual boost.
Some say that losing the ability to see stars means losing a vital spiritual and cultural resource, one that has fueled artistic endeavors, guided religions and stimulated scientific advances.
"The vision of the night sky has been triggering meditation in human beings as long as we've been on the planet," said poet Alison Hawthorne Deming, director of the University of Arizona's Poetry Center. "The night sky induces wonder, and wonder is one of the capacities that makes our lives beautiful."
If children grow up without seeing the Milky Way, they "have been robbed of an experience that might make them more thoughtful, more filled with wonder - and that means they're less connected to sources of deeper meaning," she said.
The ancients saw the heavens as a place of permanence and perfection, the home of the gods, said UA historian of religion J. Edward Wright, author of "The Early History of Heaven."
"People looked to the stars, and they saw this image of things that really work," he said. "The priests, the astronomers can predict when the stars are going to arise."
Not being able to see the stars also means losing "all manner of inspiration that humans have received by looking up at the stars at night - art, romantic inspiration, a sense of one's place in the cosmos," he said.
Images of stars permeate everyday life, pointed out Tucson folklorist "Big Jim" Griffith as he reeled off a series of words and song titles - starry-eyed, starstruck, stardust, don't let the stars get in your eyes - and then recited:
first star I see tonight
I wish I may I wish I might
have the wish I wish tonight
Even our lucky numbers come from the heavens, said retired UA classics Professor Thomas Worthen.
"The number seven - a lucky number - comes from the planet Mercury," he said, explaining that Mercury passes the same celestial signposts every seven years.
"The ancients knew that, but we've forgotten. The (biblical) seven years of plenty, the seven years of famine, all of these come from the stars, this lore."
The desire to learn about the heavens drove the ancients to develop their astronomical abilities and ultimately fueled the invention of mathematics by cultures as varied as the Greeks, the Babylonians and the Mayans, Worthen said.
"This is what gave us mathematics," he said. "Trying to figure out a calendar that works for both the moon and the sun."
The desire to learn more about the heavens drove some of the earliest scientific investigations and created mathematics, a discipline essential to modern science.
Now a relatively modern technology - the electric light - threatens the ability of modern-day astronomers to probe the faintest portions of the night sky.