Dim Darkness and the Problem of Light Pollution
By Kate Burns
Earth at Night is a mosaic woven together by NASA of around 400 satellite photos of Earth at night during the year 2000. A star’s view of the planet in darkness is rare to see; the Lite Brite spread of humanity’s habitation seems reminiscent of the stars themselves. Human beings have been so successful at spreading, the success is visible from space. Those glittering gems of light seen from space are, in reality, massive collections of street lamps, porch lights, security lighting, lit signs and billboards, and every manner of outdoor lighting combined. All of those lights are built to illuminate something for a specific reason; it seems unlikely that said purpose is to attempt to illuminate space itself. Yet they shine on, costing us money and natural resources. Moreover, they impair our ability to see the real stars from Earth.
Earth at Night is the poster child for the issue of light pollution. Light pollution is simply artificially generated light illuminating areas not intended to be illuminated due to poor lighting fixtures. “Human-produced light pollution not only mars our view of the stars; poor lighting threatens astronomy, disrupts ecosystems, affects human circadian rhythms, and wastes energy to the tune of $2.2 billion per year in the U.S. alone” (International Dark Sky Association). The circadian rhythm is an intrinsic, trainable 24-hour cycle of activity of an organism. A human being needs to sleep on average six to eight hours a day, and the majority of the population sleeps during the hours of the day when the sun is down. This is not due to voluntary, daily choices to sleep during the night, but rather the circadian clock of the individual being set to induce sleep in darkness. But without darkness, the clock may miss its cue.
The threat to darkness is artificial light, which comes in three major forms: glare, light trespass, and sky glow. Light trespass is a version of trespassing most people regularly tolerate. Before you go to bed, for example, you may close the blind or curtain of the windows in the bedroom to reduce the glare of outside light during your sleep. Imagine this was any other sensory intrusion: having to put in earplugs because the neighbor is loud, or having to cover your nose before sleep because the neighbors place their garbage directly outside your window. Most would lodge a complaint with the neighbors, to say the least. The light you close your blinds to is trespassing into your bed: unwanted, unneeded, and out of your control. The scenario may be thought of as simply annoying, but artificial light has been shown to harm human health. A Professor at Harvard Medical School, Steven Lockley states “… light intrusion, even if dim, is likely to have measurable effects on sleep disruption and melatonin suppression. Even if these effects are relatively small from night to night, continuous chronic circadian, sleep and hormonal disruption may have longer-term health risks” in a booklet by the Campaign for Dark Skies. In 2009, the American Medical Association voted unanimously to support efforts to control light pollution.
Sky glow is an overall brightening of the night sky, through stray light traveling skyward. “The problems of sky glow is that it reaches a considerable distance. In Delaware [county], you have people adopting light pollution laws,” explains Dr. Shields of the Ohio University department of physics and astronomy and winner of the Athens ‘Friends of the Stars’ award. “Local control does have a good impact, but it is a far larger problem.” The intensity of sky glow is more pronounced under cloud cover. The overall brightening of the night sky can confuse wildlife. “Behavior governing mating, migration, sleep, and finding food are determined by the length of nighttime. Light pollution negatively disrupts these age-old patterns” (International Dark Sky association). Reptiles, mammals, and amphibians can all become disoriented as to when it is darkest/the safest time of night to move, forage, reproduce and avoid predation. Birds and moths are drawn to artificial light sources, so much so as to draw them off migratory path ways and kill many either through collision with the light source or exposure to predators. It is not uncommon to take a late night stroll here in Athens and hear birds chirping.
All of these forms of light pollution amount to light illuminating places it doesn’t need to, chiefly the sky. Americans waste billions of dollars in energy costs, to no one’s benefit by installing inadequate light fixtures. “Well designed fixtures will save you money because what’s good for light pollution is good for energy. On the other hand some of these polluting lights are the cheapest and people buy them not thinking,” says Dr. Shields. A well-designed fixture, simply put, is a light fixture that directs light to the area it is there to illuminate and all light is directed below the horizon. That is, the maximum reach of the light should be less than 90 degrees to the ground. Compared to inefficient lighting giving off light pollution energy is conserved and money is saved with fewer lighting fixtures with lower to illuminate an area. Light fixtures that will not contribute to light pollution may be advertized with the International Dark Sky Association’s seal of approval.
The IDA is close to the heart of the Southeast Ohio Astronomical Society. The members of the society share only a passion about astronomy and star gazing, and many helped the city of Athens, Ohio pass a Light Pollution Ordinance in 2003. The ordinance is a law requiring all new public construction to use approved light fixtures. Private developments in development are reviewed by city administrative who recommend city laws be met. The most recent display of implication for the ordinance is in the Richland Avenue roundabout, which opened in July 2010. The light fixtures on the roundabout are all down shining lights. The new Richland bridge will also have down shining light fixtures, reports Andy Stone, Director of Athens city street maintenance. “The tricky thing about the movement is that it is a constant battle between public safety and light pollution advocates,” says Stone. Dr. Shields addresses Ohio University’s contribution to light reduction. “We’ve spent quite a few years talking to people at OU planning committees and they have been responsive. You will see the outdoor lamps have many different generations across campus. New sport lighting is well shielded.”
The light pollution ordinance of the city of Athens is one of the only laws like it in Ohio. The benefits of light pollution laws are significant and can reach individuals, and whole communities. The aid to wildlife, human health, and fossil fuel consumption is extremely substantial for little effort. The last added benefit is more qualitative; the darker the sky the clearer the stars.