JAKE LACEY/Arizona Daily Wildcat Byron Skinner of the International Dark Skies Association explains to chemical engineering senior Jake Messing what he sees through a solar telescope yesterday on the UA Mall. The telescope, which is equipped with an H alpha filter, allowed students to view sunspots and prominences on the sun.

Although bright lights illuminating Tucson streets and evening sporting events are helpful for students and residents alike, the light is also a curse for astronomers in Southern Arizona.

The International Dark-Sky Association came to the UA Mall yesterday to talk about the growing problem of light pollution to UA students for UA Earth Day.

John Polacheck, the vice president for the Southern Arizona chapter of the Dark-Sky Association, said light pollution affects the ability for astronomers to gaze at the stars with optical telescopes.

Too much outdoor lighting can compete with the visible spectrum of the night sky, effectively blinding optical telescopes from detecting faint stars and other cosmic objects, such as comets and asteroids, Polacheck said.

Polacheck said Pima County has an aggressive light pollution ordinance, which strictly regulates lighting on any private building to minimize light pollution. The regulation also concerns wattage and direction of the light, most importantly, that it's angled down or toward the event. But, Polacheck said outdoor lightning still poses a problem for Tucson astronomers.

"There is an enormous amount of wasted light," Polacheck said.

Polacheck said light trespass, which is when outdoor light leaves your property and shines somewhere else, is one of the largest problems for amateur astronomers. He estimated local sports parks contribute almost 25 percent of all light pollution in Tucson with the use of unfocused light fixtures.

Polacheck compared images from two local sports parks, one with focused lighting and another without focused lighting. With focused lighting, the park offers good lighting for those in the park but does not allow light to shine into the sky needlessly.

"Clearly some simple shields could fix that," Polacheck said about the park using unfocused lighting.

Polacheck said another concern for IDSA was trying to promote the use of low-pressure sodium lights over other forms of lighting. He said low sodium lights contribute low amounts of glare and are only part of a small portion of the spectrum, which astronomers can easily filter out with their instruments.

"The cheaper fixtures are also the appropriate ones," Polacheck said.

Scott Davis, the chief operating officer for the International Dark Sky Association, said the group formed in 1988 by David Crawford, an astronomer at Kitt Peak National Observatory southwest of Tucson.

Davis said Crawford formed the group in reaction to the growing concern that light pollution would have on the viability of local optical telescopes, including Kitt Peak.

Melanie Levine, a media arts senior, said the IDSA booth "was really cool."

Levine looked through a solar telescope for the first time ever to gaze at the sun, and she said she was surprised at what she saw.

"I didn't realize it would look so red," Levine said.

A filter used by IDSA to view the sun turns the bright white image of the sun to a red hue.

Levine, who took a tier-two astronomy course at the UA, said she was unaware of how outdoor lights can affect astronomers.

"We didn't talk about light pollution," Levine said.

Priya Sood, a business administration and accounting sophomore, said the booth was informative.

Sood said IDSA makes a persuasive argument for private businesses to change to low sodium and focused lighting.

"It's better (for everyone) in the long run," Sood said.

The UA Recycling and Waste Management Program and the Arizona Student Recycling Association sponsored the Earth Day event.

Participating Earth Day groups included BioCats, Campus Greens, Friends of the Sonoran Desert, Students for the Ethical Treatment of Animals, the UA Arboretum, the UA Tree Ring Lab and the Vegetarian Resource Group of Tucson.