Doug and I just returned from a two-week camping trip in Nova Scotia. One dark, clear night we saw an amazing sight. Out on Cape Chignecto, there were no brightly-lit advertising signs, streets, parking lots or commercial properties to obscure the night sky. The lack of artificial sky glow revealed an awesome array of glittering stars.
Artificial nighttime lighting affects biological rhythms of humans and animals. It also reduces our ability to enjoy and study the night sky.
Light pollution is light that strays from its intended area. It is a side effect of industrial and residential development, and a significant and growing problem worldwide. There is no place in the continental U.S. without light pollution, which would earn a Class 1 on the Bortle Dark-Sky Scale. Utah’s Natural Bridges National Monument is the only spot that rates a 2 on the Bortle Scale. While some airline pilots refer to our area in The Last Green Valley as the “dark spot” between the sprawling Boston-to-Washington corridor, it seems like twice as many stars were visible in the Nova Scotian sky. (See what this looks like from space). In the inner city, the only celestial object that can be seen well is the moon, the planets and a few of the brightest star clusters. When the lights went out after a 1994 earthquake in Los Angeles, many residents freaked out when they looked skyward and saw a “giant silvery cloud” over the power-less city. They were viewing the Milky Way for the first time.
In addition to interfering with stargazing, excessive use of light wastes energy. The City of Calgary reduced spending on electricity by more than $2 million a year by converting to full-cutoff, reduced-wattage street lights. (Source: CBC News) Glare produced by bright or poor-shielded lights can blind drivers and pedestrians and cause accidents. Excess or obtrusive light can affect health and sleep. It can also disturb ecosystems.
Little research has been done on how artificial nighttime lighting affects the biological rhythms of animals. However, one study indicated that the movements of tiny invertebrates called zooplankton that live in lakes may be impacted by nighttime lighting used around lakefront homes. Normally these creatures rise up to feed at night, and by day drop down to the bottom of the lake to escape predators. If lights are bright, they do not come up, which allows runaway algae growth. Birds migrating at night can be attracted to, confused by, and subsequently collide with brightly-lit structures. Lights along beaches may keep sea turtles from coming ashore to nest. Hatchling turtles usually emerge in the nighttime and orient themselves towards the brightest area. If beach lights beat out the light reflected off the ocean’s surface, hatchlings can become disoriented. They crawl away from the ocean towards artificial lights to be run over by cars or die from exhaustion, dehydration or predation.
If you want your children to be able to see more than street lights at night, here are some simple ways to reduce light pollution:
- Avoid floodlighting and unshielded wall packs. Do not create "light trespass" onto neighboring areas. Install energy-efficient, fully-shielded lighting fixtures outdoors. They reduce glare by directing light downward where it is needed for safety, security and visibility. See drawings of good and bad lighting by Peter Talmage, courtesy of Sky & Telescope Magazine: Example 1 | Example 2
- Install lights only where necessary. Do not turn on lights when they are not needed. If possible, use timers, sensors or other controls to turn out the lights when no one is around.
- Use high-efficiency lamps when possible. They last longer and use less energy than regular lamps. Look for low-pressure or high-pressure sodium lamps with full-cutoff luminaires. They are not perceived as natural light by creatures, and thus minimize ecological disruptions.
- For post-style lamps, use a fixture with an opaque top to help direct light downward. For billboards and signs that are illuminated at night, use top-mounted lights focused downward onto the board.
- If the American flag is flown at night, out of respect and by law (the Flag Code) it must be properly illuminated. A small, solar-powered spot mounted on the pole works nicely.
You can also work with your community to create regulations on nighttime lighting. The International Dark-Sky Association offers model language to reduce light trespass. Woodstock, CT has a requirement that “No sign illumination shall be permitted between the hours of 10 p.m. and 6 a.m." Unfortunately, many sources of night time lighting are grandfathered in. However, businesses (and residents) who want to be good neighbors can still comply.
By the way, Google Earth (www.earth.google.com) has launched a new feature called “Sky.” This virtual telescope weaves together sky surveys from observatories and the Hubble Space telescope. You can look at the earth’s surface and then turn the perspective to see the entire sky. Another free web-based planetarium can be found at WikiSky.org.
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