Posted by: columbiahighlands | April 4, 2011

Celebrate International Dark Sky Week!

You may not have even realized it, but one of the world’s most rapidly diminishing resources is darkness.

Photo caption: In the Columbia Highlands, 14 roadless areas are rated Class 2—the darkest night skies in North America--over all or most of their area (South Fork Mountain, Salmo-Priest A/B, Twin Sisters, Thirteenmile, Deer Creek, Cougar Mountain, Grassy Top, Bodie Mountain, Clackamas Mountain, Jackson Creek, Deer Creek, Profanity, Cougar Mountain, Bald-Snow). Image courtesy of National Oceanic and Atmospheric Administration.

Light pollution caused by poor outdoor lighting, coupled with air pollution, which makes the atmosphere most reflective, has effectively washed out the night sky overhead—a phenomenon called “sky glow”.

Today, two-thirds of Americans cannot see the Milky Way from their backyards. A resident of New York City can see less than one percent of the celestial bodies that illuminated the night sky prior to European settlement.

Many amateur astronomers use the Bortle Dark-Sky Scale to rate the night sky. Named after Sky and Telescope columnist John E. Bortle, the nine-point scale measures numerous criteria, among them the brightness of the faintest celestial objects visible without magnification. Class 1 are the darkest nighttime skies. By comparison, New York City rates as Class 9; most urban/suburban areas in the United States rate as Class 5, 6 or 7. One would have to travel to remotest Chile or the Australian outback to experience true Class 1 night skies, and only a few places in North America still rate as Class 2.

Not only has sky glow diminished the drama of the dark night sky, but reams of recent research show that excessive nighttime lighting has wide-ranging impacts, from bird migration patterns to human health. Several studies have even shown that excessive nighttime lighting may disrupt the circadian rhythm, the body’s internal clock, which may alter the body’s production of hormones and result in increased cancer risks.

The International Dark Sky Association (ISDA) was formed in 1999 to promote the preservation of our nighttime skies. This week, April 1st through 8th, the ISDA celebrates International Dark Sky Week. Take this opportunity to celebrate the power and mystery of the sky overhead.

Fortunately, in the Columbia Highlands we are blessed with vast reaches of undeveloped land over which the night sky still shines as brightly as it did when David Thompson first floated down the Columbia River in his canoe. From the Salmo-Priest Wilderness and surrounding wild areas to the Kettle Crest near Republic—some of the darkest night skies in North America can be found in the Columbia Highlands. Take time this spring and summer to enjoy our local wildlands and our local dark night skies!



  1. I hope there will always be places with dark skies!

  2. […] Friends of the Columbia Highlands on International Dark Sky Week: […]

  3. Hi,
    Just curious where the rating information came from? I tried looking on the IDS website without much luck.
    Thanks for the post!

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