Understanding Light Pollution


What is good lighting?

The diagrams above are shared from “Good Neighbor Outdoor Lighting” by the editors of Sky & Telescope Magazine. We begin to understand light pollution when we are conscious of our environment. Poor outdoor lighting shines onto neighbors’ properties and into bedroom windows, reducing privacy, hindering sleep, and giving the area an unattractive, trashy look.


Understanding Light Pollution and Energy Waste

Many outdoor lights waste energy by spilling much of their light where it is not needed, such as up into the sky. This waste results in high electricity costs. Each year we waste more than a billion dollars in the United States needlessly lighting the night sky. It’s not only light pollution we’re talking about here.


Understanding Light Pollution and Excess Lighting

Some homes and businesses are flooded with much stronger light than is necessary for safety and security. In their recent book, “Fighting Light Pollution,” by the International Dark Sky Association a case is made for less light not more light when it comes to security. They say, “It is common for people to talk about or describe their problems and needs using solution language. So we might say we need more light when what we actually mean is that we have trouble seeing in a dark location. Impediments to visual accessibility might be the real problem. This logic suggests that in the case of lighting, what people really desire is to see things, not have more light.

“When used improperly, lighting itself impedes vision through glare or the veiling of a subject. More light is not necessarily better. This confusion about the objectives of outdoor security lighting directly affects the way many such systems are designed. Too often, these systems feature too much lighting, which does little to enhance security and can, in fact, hinder it.”


Use only the light needed

Don’t over-light, and don’t spill light off your property. Specifying enough light for a job is sometimes hard to do on paper. Remember that a full Moon can make an area quite bright. Yet some lighting systems illuminate areas 100 times more brightly than the full Moon! More importantly, by choosing properly shielded lights, you can meet your needs without bothering neighbors or polluting the sky

Aim lights down

Choose “full-cutoff shielded” fixtures that keep light from going uselessly up or sideways. Full-cutoff fixtures produce minimum glare. They create a pleasant-looking environment. They increase safety because you see illuminated people, cars, and terrain — not dazzling bulbs.

Install fixtures carefully to maximize their effectiveness on the targeted area and minimize their impact elsewhere

Proper aiming of fixtures is crucial. Most are aimed at too high an angle. Try to install them at night, when you can see where all the rays actually go. Properly aimed and shielded lights save money. They can illuminate your target with a low-wattage bulb just as brightly as a wasteful light does with a high-wattage bulb.

Put lights on timers where feasible

Business lights should turn off after closing time. Put home security lights on a motion-detector switch, which turns them on only when someone enters the area; this provides a great deterrent effect!

Replace bad lights with good lights!

You’ll save energy and money. You’ll be a good neighbor. And you’ll help preserve our view of the stars.

The first and most important thing we can do about light pollution is to purchase dark sky friendly lighting fixtures.

A group calling themselves The Needless Light Campaign has put together a few entertaining and educational short videos explaining in pictures what light pollution is and how it affects us.

For more information about light pollution, visit the International Dark Sky Organization.

Understanding light pollution is important for everyone, even those who are not interested in astronomy. Organizations like the International Dark Sky Association believe that light pollution is not unsolveable. It is a matter of what kind and how much lighting we choose to use and where we focus it.

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