Millions of people in the United States and billions worldwide are unable to see the Milky Way.
The fading universe
Star-spangled nights should be available for all to see and enjoy, but for most are barely visible. Light pollution, like a milky cataract, is blurring our celestial vision.
Twilight waned as the night rose in the east. Acrobatic bats swooped and rolled for insects. My telescope, pointed skyward, was poised for an evening of stargazing. The night lights and constellations began to appear and brighten. Then a false twilight cast by communities near and far started to spread and intensify. Light pollution, way out here in the country. Bright enough at my location to severely dim the stars above the eastern and southern horizons, and erase stars altogether in the southwestern sky. Our dark skies and starry nights are much more faint.
Light pollution has been deleting our view of the Milky Way galaxy and the universe beyond since the 1950s. It's as though we've been building a shield of light around the planet afraid, perhaps, to view the infinite that surrounds us even as we seem to fear the dark here on Earth.
Light pollution is evident everywhere. Even in a rural state like Wisconsin, the ubiquitous light domes of our communities are conspicuous. Far out to sea "the sky is not as dark as it was even 20 years ago," according to marine ornithologist Dr. Richard Podolsky. Coastal cities, offshore oil rigs, cruise ships and fishing fleets all contribute to this phenomenon.
Though still considered a nonproblem by many, light pollution is more than a minor nuisance. It wastes money and energy. It contributes to global warming and is recognized as a health hazard. Here in the United States about $2 billion a year is spent on lighting that creates useless sky glow. Wasted lighting is responsible for about 38 million tons of our annual carbon dioxide emissions. A lot of megawatts are generated, distributed and then thrown away on unwanted light. (Read more at International Dark-Sky Association.) Studies of disrupted hormone production, brain activity, cell function and other changes in birds, bats, frogs, fish and people have been ascribed to light pollution.
Light pollution, defined by the IDA as "excessive and inappropriate artificial light," has four components that can act independently or in combination:
Light trespass describes when light falls in places where it isn't intended, wanted or needed. Examples include home security lights that spread a wide beacon and stray onto neighboring properties, street lights that are poorly collimated and illuminate much more than the streets, and parking lot lighting that wanders away casting light in too wide an area.
Glare is excessive brightness. This causes visual discomfort and the overload will actually decrease visibility. So-called mercury vapor "farm yard" lights are dazzling sources of glare.
Clutter is a profuse grouping of light sources. Major tourism strips, outdoor sports arenas and other places with groups of attractions contain notable examples. Developed strings of commercial properties like Bluemound Road between Waukesha and Milwaukee are very brightly lit at night. Indeed, you can find examples in the vast majority of communities with clusters of businesses, car lots and malls. The proliferation of clutter greatly contributes to light pollution.
Urban sky glow is the brightening of the night sky over inhabited areas. This is what I see from my rural home in western Wisconsin. Because of sky glow, millions of people in the United States and billions worldwide are unable to see the Milky Way. Indeed, photographed from satellites, a poster entitled "Night View" shares a stunning image of Earth that clearly shows how urban sky glow interferes with our view of the heavens. You can see many such images by entering "Night Views of the United States" in a computer search engine.
Given that light pollution can be expensive, wasteful and aesthetically unpleasant, how did this phenomenon come to be and why does the overlighting trend continue?
Since the first campfires and the feeling of safety and warmth they brought, people have practiced a philosophy that "more is better." Homeowners, lighting contractors, builders and community officials alike are often still stuck in a rut that bright night lighting is "the way we've always done it." We play on fears and believe that more lighting prevents crime. In fact, nobody really knows. Still, the ideas are well entrenched and it's difficult to convince people to cut back or to contain night lights.
Education, of course, is a first step. Second, too few people have spent time far enough away from community lights to appreciate what a dark sky can reveal. Third, reclaiming the night sky is a long-term process. It can be expensive and time consuming to replace outdated street lights, residential lights and business lighting. It's obvious that reductions will only occur gradually, just as the escalation took decades.
Still, some steps can be taken now. If you're interested in reducing your own "photon footprint" while improving efficiency, search around a little and notice where you see softer, more pleasant lighting when you take night walks. Residential and commercial bulbs and fixtures are available. IDA offers helpful lighting tips.
Don't overlook your local electric utility as a source of help. Many electric utilities and co-ops are actively promoting power conservation and efficiency. There are plenty of alternatives to inefficient, dusk-to-dawn mercury vapor "security" lights that cast a pall of glare, light trespass and sky glow.
Convincing community officials of the need to enact outdoor lighting codes is an essential step on the road to taking back the night. It takes persistence and education. As of this writing, Wisconsin Skies lists only 33 Wisconsin communities that have enacted lighting ordinances, and the quality of those ordinances vary from comprehensive to a mere mention of the subject under the zoning subsections entitled "nuisances." Until cities, villages and towns take meaningful, enforceable actions to halt and reverse light pollution, the chances for the widespread return of Wisconsin's dark skies are slim, or should I say "dim?"
Yet practical solutions for halting light pollution are available now, further research and development isn't needed. Communities can take practical actions to achieve the goal of efficient, effective and reduced outdoor lighting.
Ironically, though communities often think of extra lighting as providing a safer environment, there are safety concerns from overlighting as well. Communities should think about using only as much light as is needed. Glare is visually uncomfortable and reduces visibility. Too much light interferes with night vision, impeding one's ability to see beyond an illuminated area. Reduced lamp wattage can actually increase visibility and safety while reducing costs.
Around your home, use lighting only where and when it's needed. Timers and motion detectors can help achieve this end. Consider where and what you are illuminating and why you are doing so. Think about how your lighting affects neighbors just as you now try to control noise to minimize disturbances.
Shine lights down rather than up. Well designed fixtures aim light where it's needed – towards the ground. They are fully shielded and can include "cut-off" units that don't allow light to leak towards the sky. Such fixtures for residential and commercial use are featured in the IDA Fixture Seal of Approval program.
Use efficient light sources. Because fully shielded fixtures direct the light to only where it's needed, lower wattage lamps can often supply sufficient light for the task. This is good for the environment, good for the wallet and provides more efficient, effective and pleasing outdoor lighting results.
Light pollution can be stopped and reversed, but only if we exercise the collective will to do so. The glow from our "campfires" can be dimmed without compromising our safety and security. Perhaps, over time, the fading universe will again be visible everywhere, illuminating our sense of awe and sparking our imaginations as it has done since humankind first gazed in wonder at the nighttime sky.
Kurt Sroka writes from Somerset.