美国国家公共电台 NPR（在线收听）

Idaho Dims The Lights For One Of The Best Night Skies Anywhere

SCOTT SIMON, HOST:

On a clear night in central Idaho, you can see the Milky Way. That's because people there have made an effort to keep the night sky dark - dark enough, they hope, to earn an official seal of approval. Max Guilhem (ph) - Matt Guilhem of Boise State Public Radio explains.

MATT GUILHEM, BYLINE: The conditions are perfect as Steve Botti, an astronomy enthusiast and city councilman for the tiny mountain town of Stanley, holds his sky quality meter to the heavens. It's a cloudless night, and the moon has set behind the Sawtooth Mountains as he assesses the darkness of the sky.

STEVE BOTTI: A reading of 21.75 or higher is considered by the Dark-Sky Association to be exceptionally dark - 21.76.

GUILHEM: With the darkest dark being 22 magnitudes per square arc second, the sky just outside of town is pristine. The region surrounding the outpost would be part of a proposed Central Idaho Dark Sky Reserve, the first of its kind in the U.S. Botti, who's been leading the charge to land Idaho the reserve for two years, says to get a similar view, you'd have to travel - far.

BOTTI: Well, there's a dark sky reserve in Namibia in southern Africa, which is very remote. It's a desert region, no cities anywhere close by.

GUILHEM: It's one of just 11 reserves around the world recognized for the quality and depth of the darkness.

JOHN BARENTINE: We have five designation categories, and I would say it is the most difficult of the set.

GUILHEM: John Barentine is the program manager for the Arizona-based International Dark-Sky Association. That's the group that vets and credentials exceptionally dark locales.

BARENTINE: In the case of the Sawtooth, it was some folks from Stanley. They told me that they view the nighttime darkness and, you know, the ability to see the Milky Way as something that is definitive of their part of the state and their part of the country.

GUILHEM: About 50 miles southeast of Stanley - on the other side of a high mountain pass - is Ketchum, a resort town that was also the final home of Ernest Hemingway. After enacting its first ordinance to curb light pollution and protect the sky in 1999, Ketchum was recognized by the international association in October as an official dark-sky community. Nina Jonas, the mayor of the town of almost 3,000, says the criteria for the designation are quite specific.

NINA JONAS: We can't have any light going straight up, so you have to have a cap on your light shutting it down. Then you get into the argument of lumens, wattage, foot-candles. So - brightness - let's just call it brightness. There's a brightness degree, and then there's also a color degree.

GUILHEM: In other words, lots of rules.

On a recent chilly afternoon, Judy Berg is picking up groceries in downtown Ketchum. She and her husband have lived in the city for 25 years. While it might seem burdensome, Berg says following the dark-sky ordinance has become second nature to residents.

JUDY BERG: Everybody seems to comply with it. I think the ones who don't are people who just move here and aren't familiar with it - haven't lived with it. When they realize how nice it is, then they're compliant.

GUILHEM: In three years on the job, the head of Ketchum's planning and building department says the city hasn't issued a single citation for lights out of compliance. The cooperation of the people of Ketchum is one reason you can reliably see the Milky Way from here on so many clear nights. And soon, all the paperwork and all the measurements could pay off. A designated dark sky reserve could bring a whole new crowd of celestial tourists. The International Dark-Sky Association is expected to make a decision about central Idaho by the end of the year.

For NPR News, I'm Matt Guilhem in Ketchum, Idaho.