NIGHT LIGHTS : Astronomers Hope Law Will Keep Sky Dark

One of the nation’s toughest ordinances controlling light pollution from private sources became law last week in San Diego County.

But there was little visible effect from atop this mountain at the observatory scientists said would cease to be a useful research tool without the restrictions.

The astronomers cautioned, however, that the 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 county’s unincorporated area and makes mandatory the use of low-pressure sodium streetlights in future developments.

The ordinance “gets to the real root of our problem,” said Robert Brucato, assistant director of the Palomar Observatory, which is operated by the California Institute of Technology. “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, even 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 untamed wilderness on Mt. Palomar.

Exhausted from 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 burgeoning communities that had sprawled so quickly across the Los Angeles Basin. And as scientists looked to locate 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 from Pasadena. This year, the transition becomes complete as the Carnegie Institution of Washington, D.C., will close the once-famed Mt. Wilson Observatory, and research monies will be transferred to a facility in the Chilean Andes.

“Astronomers always have had to stay one step ahead of factors that could ruin their research,” said Brucato. “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, but they are moving to block the glare before it’s too late. The county’s private lighting ordinance, they hope, is a precursor of changes in cities and counties throughout Southern California.

Bitterly Opposed

Earlier last year, Caltech astronomers and scientists from San Diego State University and the University of Illinois, co-owners of an observatory on nearby Mt. Laguna, succeeded in their intense lobbying effort to convince the San Diego City Council and county Board of Supervisors to convert streetlights to low-pressure sodium lamps, which are known for the low-glare, pale yellow light they emit.

The county’s new law controlling private lighting was bitterly fought by advertising and lighting industry representatives but generated little public opposition. “We were encouraged by that,” Brucato said. “It shows that people have learned they can live with the low-pressure sodium lights, and that they realize the importance of our research.”

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 a Kitt Peak observatory near Tucson, Ariz.--to other areas. Preliminary discussions already have begun with the City of San Diego, where the City Council is expected to take up the issue this spring.

Brucato also hopes to convince 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 streetlights is not enough.”

Nothing Changed

True to Brucato’s estimate, 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 that the 11 p.m. curfew was adhered to. The county has designated workers from its Public Works Department to enforce the ordinance, and they are empowered to issue misdemeanor citations to people 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. It’s an investment in our future.”

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.

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

Only when looking toward unpopulated, desert areas, did the blackness of the sky extend all the way to the ground.

“You can only imagine the effect any kind of light has on equipment as sensitive as the telescopes,” Brucato said. “Every little bit of light impedes the work we’re trying to do. There is no magic limit beyond which light pollution ceases to be a problem for us, although it does intensify the closer it is to our telescopes.”

Scientists began worrying about the darkness of the sky at Palomar in the early 1980s, after a decade of unprecedented growth in the rural regions of San Diego County. “The county’s population doubled since 1972, and the light pollution grew even more than that,” Brucato said.

“We are not in the same situation as Mt. Wilson, where important research had become all but impossible to perform,” he said. “But we realized we couldn’t let the situation get away from us like they did or we’d lose Palomar before we had a chance to get control of the situation.”

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.

Controlling that extra light without tough laws such as the county’s new private lighting ordinance would be impossible, Brucato said. “Light is our meat and potatoes,” he said. “We’re not involved in research where the subject of our study can be moved somewhere. All we can do is sit on this rock, look out, and try to figure out what the heck goes on out there.”

Extraneous Light

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.

“Just because there’s a clear, dark sky doesn’t mean it’s a good sky (for astronomical research),” Brucato said. “The sky already has a natural air glow, caused by certain atmospheric conditions, that is millions of times fainter than what you could see with the naked eye, but which makes a big difference when you’re deciding where to place a telescope. You want an area, like Mt. Palomar, where that air glow is at a minimum.”

In the future, scientists will look to Hawaii and to certain areas in the Southern Hemisphere to place their new equipment. Caltech’s newest, most sophisticated, telescope 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.”