New Mexicans and Arizonans who for decades have seen our night skies go from dark to hazy-bright, and who have led efforts to dim the glare, can take heart that we're not alone:

The cover of National Geographic's November issue is an aerial photo of Chicago at night — a monument to mankind's ability to turn darkness into day. The stars are entirely blotted out of the huge city, its suburban fringe and the farmlands far to the west.

Well, of course; that's to be expected from America's populous eastern third — and night skies free of smears are what send tourists out our way, many of them so delighted with our celestial wonders that, when they get back home, they pack up and move here.

But on pages inside the respected magazine are other portrayals of light pollution, including a shot of the Bonneville Salt Flats, their whiteness aglow — and, filling the eastern horizon, a crepuscular light: It's from Salt Lake City, Utah, more than a hundred miles away.

In contrast stands a photo from another part of our neighbor state: Natural Bridges National Monument. Above Owachomo Bridge is a skyful of stars, and the gases of the Milky Way — something fewer and fewer Americans can even see.

To preserve the nocturnal beauty of that part of the Four Corners, the International Dark Sky Association has designated Natural Bridges the first Dark Sky Park. Presumably, the unofficial subtitle could lead to restrictions on light pollution.

It would be a promising step: As the magazine's article notes, "of all the pollutions we face, light pollution is perhaps the most easily remedied."

Half a century ago, astronomers in Arizona realized the threat of night lights to their ability to peer beyond our atmosphere. They had built telescopes in the mile-and-a-half altitude of Flagstaff, and way out in the desert west of Tucson.

But Tucson, like so much of the Sun Belt, was on an extended construction-and-development boom: The glare of its lights soon rose above the mountains surrounding it — and the scientists of Kitt Peak National Observatory, 50 miles west, were properly concerned.

Most of those científicos live in Tucson, and Kitt Peak has working relationships with the University of Arizona, a major economic and social force in southern Arizona — so 40 years ago, the city adopted some sensible night-sky ordinances. Downward-aimed, shielded-top streetlights made their appearance, and the brightness of commercial lighting was reduced to the luminary equivalent of a low roar.

This followed a civic campaign in Flagstaff, whose leaders were made aware of that growing city's effect on Lowell Observatory, in the mountains above, where Pluto was discovered in 1930.

Here in New Mexico, astronomy is one reason for the small, but promising, steps we've taken to protect our night skies. Tourism is another. But there've been hints at still other reasons for dimming down — and the Geographic's Verlyn Klinkenborg nicely stated them: Lighted nights have their effects on animals.

Cited were sea turtles, which have depended on darkness to do their nesting on beaches. Seaside resort developments have taken a huge toll on those creatures and their hatchlings. Frogs, toads, birds of many kinds and so much other nocturnal wildlife are suffering similar fates.

Oh, and don't forget homo sapiens: Darkness, we're learning, is something our biological clocks count on. Altering our wake-sleep oscillation, says Klinkenborg, is a bit like altering gravity — and the biological toll is now getting serious consideration. Scientists are looking into links between light pollution and some cancers — notably breast cancer.

So it seems the Santa Fe City Council and the New Mexico Legislature are onto something with their pioneering protections of the night sky. But such thoughtful steps as replacing upward-glare light fixtures with the many kinds of caps and domes now available shouldn't have to be a matter of law: Our night skies are a treasured part of life in this state; protecting them should be a shared effort, including one in our Legislature to strengthen our state's laws.