Karen Sherper Rohs

I was first introduced to the concept of light pollution during an astronomy class in college. Although I had sympathy for the astronomers and the difficulty presented to their work as the areas around the observatory became increasingly lit at night, it didn’t seem very relevant to me personally. Until I moved home about ten years later. I discovered that the town five miles south of our hobby farm has so much lighting that a haze persists through the night. Some of my most vivid childhood memories include the sky — gazing into it with my brother as we waited for the school bus on early mornings, or whispering about its wonders as we came home late at night. These days the stars are more difficult to see.

Nighttime satellite image of the United States courtesy of Darksky

What is light pollution?

Light pollution is light that goes beyond where it is meant to be going or light being used when it is not needed. Three of the most serious problems in shoreland lighting include glare, light trespass, and sky glow. Sky glow refers to the washing out of the night sky due to exterior lighting shining upward and making cities “glow” at night. Examples include billboard lights that shine upward, street or parking light - ing bouncing off of pavement, and commercial or residential lighting open to the sky. Glare is the light going beyond what the fixture is meant to illuminate. This might be caused by poor design or poor installation. On shoreland, it can hamper the vision of boaters, pedestrians, and drivers and actually be a safety concern. Light Trespass is usually caused by glare; it’s the illumination of adjacent or nearby property not meant to be lit by the fixture. On the waterfront, water reflects glare from shoreland lights onto distant properties. The reflective nature of water is one of the most challenging aspects of sensible shoreland lighting!

What can be done?

• Provide adequate light for an evening activity, but don’t over-light. Choose lights that meet the needs without lighting beyond what is required for the task.
• Choose lights that do not emit light above the horizontal or retrofit existing fixtures with shields to reduce glare.
• Use high-efficiency lamps.
• Avoid dusk to dawn security lights; consider motion detectors.
• Position lights above and in front of signs, keeping the light aimed at the sign surface.
• Learn more about light pollution and recommendations for exterior lighting guidelines designed for local planning authorities.

Why care about light pollution?

The Institution of Lighting Engineers states: “All living things adjust their behavior according to natural light. Man’s invention of artificial light has done much to safeguard and enhance our night-time environment but, if not properly controlled, obtrusive light (commonly referred to as light pollution) can present serious physiological and ecological problems.” A quick scientific literature search produced studies indicating connections between artificial nighttime lighting and disruptions in migrations of birds and salmon, disruption of plant development, decreases in moth populations, behavior impact on fireflies, and disruption of turtle and frog reproduction. In addition to reducing the impact of artificial lighting on nocturnal biological activities, eliminating light pollution will reduce energy usage, save money, and reduce distraction to nighttime drivers. Perhaps less tangibly, eliminating glare will once again open up the nighttime sky for gazing by professional astronomers and amateurs alike. David Crawford, Executive Director of the International Dark Sky Association says: “Light pollution is not a matter of life and death. Yet it is important nonetheless, profoundly so. We human beings lose something of ourselves when we can no longer look up and see our place in the universe. It is like never again hearing the laughter of children; we give up part of what we are.”

Resources on Shoreland Lighting, Light Pollution, & Stars

• Sensible Shoreland Lighting: Preserving the beauty of the night. Publication by David S. Liebl, Robert Korth, University of Wisconsin-Extension.
• International DarkSky Association Fact sheets, satellite imagery, links to research, additional light pollution information, and tips for choosing exterior lights.
• University of Chicago Yerkes Observatory Photographs, presentations, sample ordinances, and additional website links.
• New England Light Pollution Advisory Group Newsletters, tips, website links.
• Minnesota Sustainable Design Guide Recommendations for exterior lights.
• University of Minnesota: Astronomy
• April 23, Wed., 7 pm presentation, Marshall W. Alworth Planetarium, Duluth. Lights of Our Atmosphere: Natural vs. Unnatural.

Posted in Care of Shoreland Property |