By Kathy Bouchard EBS CONTRIBUTOR

For nearly a week each winter month, fair skies are rinsed of all but the brightest stars by the gleaming splendor of the full moon. It is the perfect time to strap on skis or snowshoes and experience the ethereal vistas of cool white mountains touching the blue-grey heavens. Everything casts deep moon shadows and all the contours of landscape are rendered otherworldly by lunar brilliance on the snowy world. The often bitingly cold night absolutely glows.

None of this happens without pure white snow, one of the most reflective substances known. Snow bounces about 90 percent of any light which strikes it in all directions, mostly up, thus dimming the stars, but thoroughly illuminating a good deal of real estate. The reflective quality of a substance is named albedo. The albedo of the polar caps during summer months once prevented melting by bouncing light away. The albedo of loamy black dirt is almost non-existent. And perhaps our snowy albedo is under appreciated by perfectly wonderful planners and designers who don’t spend six months every year happily living with snow as we (mostly) do.

How else to explain the loss of darkness in Big Sky? Despite the need for security, publicity or safe streets, Big Sky is overlit because every watt from any bulb is nearly doubled in the presence of snow. Virtually every new commercial building is made festive with what once looked like fairy lights, but now have a more determinedly industrial aspect. Big Sky is suffering from light pollution. I can’t believe it is intentional, but it needs to be remedied. Before a single new home or business is built or completed anywhere in our community in the future, please let it be dark-sky compliant. Please let it have just enough soft lighting to be snug and cozy and no more. For those who recently built and have more light than you expected, blame the snow, and please reduce your wattage.

I have heard from a number of residents about this issue. One told me he actually moved recently to escape the lighting situation. There really is no reason for this problem to continue or worsen. If you are developing property, speak to your architects. If you are in a subdivision, including commercial subdivisions along Highway 191, learn about the International Dark Sky Association and reduce your wattage. With all the newest technology of cameras, motion detectors and security apps, bright unshaded lights are wasteful and unneighborly. If you are a concerned resident becoming more aware of the glories of darkness, share your values with your neighbors and home-owner associations. Like tanning, glittering city lights are so last century.

Preserving dark skies is one way to preserve wilderness. It increases the value of the Montana experience. Many people treasure what we are in danger of losing—the dark. We can’t control the spheres but we must control our lights, because for nearly a week each winter month, fair skies are studded with all the brightest stars in the absence of the moon, and the night absolutely glows.

One way to monitor your light is to turn on your indoor and outdoor lights per your normal usage. Walk around the perimeter of your property and see if you can see the filaments, the light producers, in any of your bulbs. If you can, then light is escaping from your property. Shades or curtains could help for indoor lighting, dark-sky compliant fixtures will help outside. And don’t forget the light magnifying quality of snow, which means a little goes a long way in winter.

Kathy Bouchard is a member of the Rotary Club of Big Sky’s Sustainability Committee. She has been a Montana resident for 20 years and is inspired to work for sustainability on behalf of her grandchildren.