The skies above most cities and towns are glowing. Artificial light sources beam a lot of their light into the sky. That makes it harder to see the heavens. And it can cause health problems, endanger wildlife, and waste both energy and money.

One big contributor to the problem is streetlights. They can be improved by adding shielding that directs their light downward, and by using the right kind of fixtures. One type of fixture that could help is L-E-Ds. They use less energy than most other types of lighting, they last longer, and their light can be concentrated on the ground, not the sky. As a result, many cities have replaced older streetlamps with L-E-Ds.

But experts on light pollution have some concerns about those fixtures. Because L-E-Ds are cheaper to operate and last longer than older lamps, some locations may increase the number of streetlights, for example.

Studies have found that, watt for watt, white L-E-Ds produce more sky glow than other types of lighting. And the color of the light can be a problem as well. L-E-Ds produce more intense blue light than some older streetlamps. That increases glare, and makes it harder for the eye to adapt when you go from a bright area to a darker one.

Experts do suggest, however, that warmer L-E-D fixtures, operating at lower levels, can light up the ground without making the skies glow even brighter.

Script by Damond Benningfield