Astronomers Hail First Victory in Keeping Palomar in the Dark

One of the nation’s toughest ordinances controlling astronomical “light pollution” from private sources became law last week in San Diego County, and there was no visible effect, even from atop this mountain, at the observatory that scientists said would cease to be an effective research tool without the law.

But astronomers said immediate results should not be used to judge the importance of the statute, which dictates that all non-essential lighting be turned off after 11 p.m. in the unincorporated area of San Diego County and makes mandatory the use of low-pressure sodium lights in future developments.

“It (the ordinance) gets to the real root of our problem,” said Robert Brucato, assistant director of the Palomar Observatory, which is operated by Caltech. “And it does so while the problem is still of a size that we can control. We see the law as an important investment in our future.”

To underscore their point--and emphasize the importance they see in their movement to adopt similarly stringent private lighting controls throughout Southern California--Brucato and other scientists tell the tale of one of their earliest predecessors on the rugged slopes of Mt. Palomar.

In 1903, as a 60-inch telescope that was then the world’s largest was being installed on top of Mt. Wilson near Pasadena, astronomers were seeking out clearer views to the heavens.

Toward that end, a young man was dispatched from Los Angeles to explore the mountainous reaches of northeastern San Diego County. It was an arduous trip--the scientist had to take a train to San Diego and a horse-drawn wagon to Warner Springs before renting a mule team for the trek into the wilderness of Mt. Palomar.

Exhausted by his journey, the man returned to the decidedly more comfortable environs of Pasadena and reported that the atmospheric conditions made Palomar’s peak perfect for stargazing. But, he concluded, the site would be unsuitable for a scientific research outpost because it was too far from civilization.

Less than 20 years later, the lack of foresight shown by that young scientist glared as brightly as the lights from the communities that had sprawled quickly across the Los Angeles Basin. And as scientists looked for a place for a 200-inch telescope, their newest state-of-the-art-tool, they realized that the basin’s light pollution ruled out Mt. Wilson.

Thus, wild though it was, Mt. Palomar was chosen for the telescope, and with that decision the center of the nation’s astronomical research shifted here from Pasadena. This year, the transition will become complete when the Carnegie Institution of Washington closes the once-famed Mt. Wilson Observatory and research money is transferred to a facility in the Chilean Andes.

“Astronomers always have had to stay one step ahead of factors that could ruin their research,” Brucato said. “They knew even in the ‘20s that Mt. Wilson was in real trouble because of all the lights.”

Today, scientists know the same thing about the Palomar Observatory, and they are moving to block the glare before it is too late. The county’s private lighting ordinance, they hope, is a precursor for cities and counties throughout Southern California.

The county’s law controlling private lighting was bitterly fought by advertising and lighting industry representatives, but it generated little public opposition. “We were encouraged by that,” Brucato said.

Buoyed by his success in San Diego County, Brucato will try to take the private lighting ordinance--which was patterned after laws adopted to preserve the dark sky necessary for an observatory near Tucson, Ariz.--to other areas. Preliminary discussions already have begun with San Diego, where the City Council is expected to take up the issue this spring.

Brucato also hopes to persuade the North San Diego County cities of Escondido, Poway, San Marcos, Vista and Oceanside to adopt the law. He also will attempt to enlist the support of the counties of Riverside and San Bernardino. “If I had the time, I’d go to every government between here and Los Angeles,” he said. “The glare from that far away affects the dark sky here. But you have to be realistic and draw the line somewhere.”

Controlling private lighting is critical to preserving the dark sky necessary for the astronomical research on Mt. Palomar, Brucato said. He estimated that 75% of the light pollution in the area comes from private sources, “so we had to get to the bottom of the problem. Just converting the street lights is not enough.”

There was no dramatic change in the darkness of the sky one recent evening after the county’s ordinance went into effect, and no brigades of light patrol officers fanned out to ensure adherence to the 11 p.m. curfew. The county has designated workers from its Public Works Department to enforce the ordinance, and they are empowered to issue misdemeanor citations to offenders who refuse to comply with the law.

“We didn’t anticipate any major differences right off the bat,” Brucato said as he led a visitor onto the catwalks atop the outside of the dome covering the massive, 200-inch telescope on Mt. Palomar. “We knew we wouldn’t notice any great change immediately, because the law is aimed mostly at controlling future light pollution, and the unincorporated area is only one small portion of the region that can affect our dark sky. But we’re starting a new movement here with the controls of private lights.”

Once on the catwalk, Brucato led the visitor on a city lights tour of San Diego County as seen from the Palomar Observatory. The brightest glare was due southwest, toward the cities of Escondido and San Diego, where a persistent glow rose from the horizon to cover about 30% of the visible sky.

L.A. Light Visible Similar, but dimmer, pockets of light emanating from the coastal communities, from Palm Springs and Rancho California in Riverside County, and even from Orange County and Los Angeles, were visible to the naked eye.

The glare from artificial sources is so prevalent when viewed through a telescope, Brucato said, that only 2% to 3% of the light seen through them comes from the galaxies. “The rest is from extraneous (unnatural) sources,” he said.

Light pollution already present at Mt. Palomar doubles the amount of time necessary to complete astronomical research. Often, Brucato said, sorting out the extraneous light can mean months of lost time for the scientists.

Research time is precious at the observatory. Caltech maintains a team of scientists and technicians at the observatory full time, but outside researchers must arrange more than a year in advance to use the telescopes. The demand is so heavy because Mt. Palomar is one of the few areas in the world where sensitive equipment like the 200-inch telescope can be used.

In the future, scientists will look to Hawaii and to certain areas in the Southern Hemisphere to locate new equipment. Caltech’s newest and most sophisticated technology will be completed within seven years at an observatory in Hawaii.

“It’s true that the most impressive equipment will not be placed at Palomar in the future,” Brucato said. “If we were deciding where to place the 200-inch now, it wouldn’t be here.

“But we feel important research can go on here for decades if we get the lighting problem under control now.”