TUCSON, Ariz.

ASTRONOMERS and others interested in a night sky unencumbered by the glare from artificial light love to tell this story: When the Northridge earthquake knocked out power in Los Angeles in 1994, numerous calls came into emergency centers and even the Griffith Observatory from people who had poured into the streets in the predawn hours. They had looked into the dark sky to see what some anxiously described as a “giant silvery cloud” over the shaken city.

Not to worry, they were assured. It was merely the Milky Way, the vast galaxy that humans once knew so well  until the glare from electric light effectively erased most traces of it from urban and near-urban skies.

It’s easy to forget, 130 years after outdoor electric lighting first cast its glow through the night, that the sky is actually full of stars. But largely as a result of a remarkable partnership between science and business that took root in Tucson during the 1970s, an idea is gaining acceptance: that darker skies can be achieved with new products and technologies. Darker skies can generate real benefits not only for astronomers, but also for businesses from gas stations and parking lots to Nascar tracks.

Because much of Arizona is mountain-studded desert with only two major urban sprawls, Phoenix and Tucson, the state has long been a center for astronomical research. It has about 30 university and federal observatories, which in turn energize a wide range of educational and for-profit scientific enterprises.