In Mendocino County's outlying areas we are blessed with an awesome night sky. If you've never looked at the Milky Way with binoculars you are missing the pleasure of star clusters unveiled. But our ability to view the night sky is in danger.
As an amateur astronomer, I find Potter Valley's night sky most delightful, except when I look southwest at the dull glow that is the Ukiah Valley. From 15 miles away Ukiah's light pollution affects our night sky. This increasingly opaque glow is evidence of energy wasted needlessly.
Most of light pollution is unnecessary and preventable. Much of it is merely careless waste from outdoor lights that are poorly designed, overly bright and improperly aimed. An estimated 35 to 50 percent of all light pollution comes from streetlights.
Most streetlights have a rounded lens below the lamp housing, the shape of which dictates how the beam is distributed onto the ground. Some have advanced optics to spread their light in specific directions; others cast their output more indiscriminately, including up into the sky.
Streetlights termed "full-cutoff," which typically have flat bottoms, emit no light above the horizontal. They reduce glare dramatically and eliminate direct uplight by sending all their light toward the ground; therefore they are more efficient and enable cities to save electricity by using lower wattage bulbs.
Many cities are adopting outdoor lighting laws. Their key points: promote full-cutoff fixtures, disallow spotlights and uplighting of buildings and signs, discourage floodlighting and unshielded wall lights, and turn off all nonessential lighting after business hours.
If you would like to help save our view of the night sky, check out the resources of the International Dark Sky Association: www.darksky.org. They have information that can help you convince planning commissions and city councils that good lighting regulations would greatly benefit everyone.
Copyright Mendocino Environmental Center 2003
Permission granted to excerpt or use this article if source is cited