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For Palomar crew, viewing space through San Diego's glow isn't too enlightening

By Marshall IngwersonStaff writer of The Christian Science Monitor / October 24, 1983



San Diego

The largest reflecting telescope in the United States, the 200-inch Hale telescope at Palomar Observatory above San Diego, may end up drowning in a sea of light.

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The ever-brightening glow of fast-growing San Diego increasingly washes out the faint light of the distant objects that Palomar astronomers strain to see.

There's an easy solution, Palomar scientists say.

What they propose is that the city use a certain kind of street lamps - low-pressure sodium (LPS) - that casts a monochromatic yellow light. This light is concentrated on a single band of the light spectrum and leaves the rest of the light spectrum uncontaminated for the astronomers.

Since LPS lamps are cheaper to run than the energy-hungry mercury-vapor lights that most of San Diego uses now, it would seem like a happy solution all around.

Not so fast, answers San Diego.

The eerie, unflattering yellow glow that LPS lights throw over the street has raised the hackles of some San Diego residents, among them City Councilman William Mitchell. Mr. Mitchell led the anti-LPS effort when the council decided against them last summer.

His objections: The light makes everything gray, black, or yellow, including people, giving them a cadaverous appearance.

Why make a ''technicolor downtown'' black and white? he asks.

Crime fighting, too, is ill-served by the LPS lights, he adds. Colors can't be identified well. He parodies a witness report about a crime on an LPS-lit street: ''A cadaver in a gray suit got into a gray car and sped away.''

The San Diego police take the same view as Mr. Mitchell, pointing out as well that the LPS bulbs are more dangerous than other types.

Worse news from the point of view of the astronomers is that the city is moving from mercury-vapor street lights to high-pressure sodium lamps (HPS).

Robert J. Brucato, assistant director of Palomar Observatory (run by the California Institute of Technology), explains that for astronomers trying to take spectrographs of stars or other celesital bodies, peering out through the glow of mercury-vapor light is ''like looking through a picket fence.''

The light is bunched on six ''pickets'' across the spectrum. Bad, but not terrible.

But while LPS only forms a single such picket, HPS casts a continuous band across the whole spectrum, flooding the night skies with contamination.

If HPS wins out in San Diego, says Dr. Brucato, Palomar will gradually become useless for pioneer faint-object astronomy, following the destiny of the Mt. Wilson observatory, rendered obsolete by light from Los Angeles.

The issue is not closed. The San Diego City Council is putting off appropriations for street lights until after a Nov. 8 election, which Caltech and the astronomers hope will strengthen their hand.