Dark Sky Lights
Light pollution is currently growing at a far faster rate than the world population, and research shows that dark sky lights are increasingly important to stop this harmful trend. Dark sky lights are the result of the dark-sky movement, a campaign to cut down on light pollution. The many advantages of the movement include that more stars become visible at night, the adverse effects of unnatural lighting on the environment is reduced, and there is also a cutback on energy usage. The use of dark sky lights benefits any community by helping to diminish the effects of light pollution.
Another important purpose of dark sky lights is to prevent “disability glare.” Poorly designed roadway lighting produces this glare, which most commonly affects older drivers. The ability of the eyes to adjust quickly to changing levels of illumination is diminished among the elderly.
Astronomers have been involved with the revelation of the need for dark sky lights. In 2012, astronomers had a hand in influencing the governor of Arizona to veto a bill which would have reversed a ban on illuminated billboards. In the study of scotobiology, the study of darkness, researchers have found that light pollution harms nocturnal animals, which need uninterrupted darkness at night. Human circadian rhythms, which affect sleep cycles, are also interrupted by light pollution.
The chief goals of the dark-sky movement which can be achieved with the use of dark sky lights are: to use fixtures in public areas which do not send light upward, to encourage communities to adopt regulations which help to prevent light pollution, and to encourage the use of fixtures that have full-cutoff mode.
The promotion of quality outdoor lighting is recognized as the best way to restore the natural night environment. The International Dark-Sky Association (IDA), formed in 1988, has developed a program for recognizing which fixtures qualify as dark sky lights. The Fixture Seal of Approval (FSA) program identifies which fixtures are dark sky friendly.
Qualities of FSA dark sky lights include light fixtures that:
- Minimize glare
- Do not pollute the night sky
- Reduce light trespass
- Are fully shielded
- Do not emit luminous output above 90 degrees in the vertical plane
Light trespass is when lighting falls where it is not wanted, needed, or intended. Glare is extreme brightness which causes visual discomfort. At high levels, glare can decrease visibility. Clutter is when there is a confusing, bright, excessive grouping of light sources, such as commonly occurs in urban areas. This type of clutter contributes to glare, trespass, and urban sky glow; it is one of the problems that can be minimized with the use of dark sky lights.
One type of dark sky lights are flag pole beacons. These fixtures provide the most environmentally friendly method of illuminating flagpoles at night. With this beacon, flags can be well lit at night without causing any light trespass and without contributing to light that is reflected onto the night sky.
Dark sky lights are available in many designs, and all fixtures designated as FSA are dark sky friendly.