Light Pollution Fact Sheet

Lighting Study Design Standards Summary: click here.

Our goal is to encourage quality lighting! We are NOT against night lighting. The 100 inch diameter telescope at Mt. Wilson Observatory, which overlooks the Los Angelas basin, is only 11% as effective as when it was built. This telescope is severely limited in its research capabilities because of light pollution. 1 billion dollars ($1,000,000,000) is wasted each year in the United States by lighting up the sky. This wasted light serves no purpose for safety, security or utility……it is simply wasted energy! We want to start NOW to preserve as best as we can the sky above Holmes Park and Hyde Observatory.

Components of light pollution include:

  1. Light trespass – Spill light coming from another property.
  2. Glare – From seeing the bright filament of an unshielded light, troublesome and dangerous.
  3. Clutter – Excessive grouping of lights, causes confusion as well.
  4. Energy waste – Costing us over One Billion Dollars a year in the U.S.A. alone.
  5. Urban sky glow – Domes of light over cities. Blocks out faint objects such as the Milky Way, Nebula and distant galaxies. Only a few bright stars can be seen from the city.


Low Pressure Sodium (LPS) fixture produces a yellow tint.
High Pressure Sodium (HPS) fixture produces a pink tint.
Mercury Vapor fixture produces a blue/white tint.
Incandescent light (bulbs) produces a yellow/white tint.

The first three types are a gas discharge source. The light is produced when the electric current passes through a container of gas, causing the energized gas to give off characteristic bands of color.

In an incandescent source a thin wire is heated to a high temperature by an electric current. This filament begins to glow and gives off light of many colors. A large amount of energy is given off as heat making the incandescent source not as efficient as the discharge source.

55 watt LPS = 100 watt HPS = 175 watt Mercury Vapor = 400 watt incandescent

For less energy a 55 watt LPS fixture can produce the same amount of lumens (light output) as the 100 watt HPS, the 175 watt Mercury Vapor and the 400 watt incandescent.

For more information, see the IDA page “Good Lighting Fixtures and Where to Get Them.”


Light from an unshielded fixture that is suppose to be illuminating the ground is also casting light upward. This is wasted light and wasted money. Some fixtures spill light onto other properties. This can be prevented by taking care in the placement and alignment of the light.


Generally speaking, if you can see a lights filament or source from a reasonable distance then the light is not well shielded.

The glare from an unshieded fixture can compromise visibility and increases the chance for accidents. Bright glare can also produce high contrast shadows. These shadows actually become cooridors of darkness that can become hiding places for potential criminals.


Excessive glare can make driving difficult and light clutter can cause distraction. For safety reasons every effort should be made to establish quality lighting on and near heavily traveled roads. Billboards and outdoor signs are designed to attract our attention. Often these are lit up with bright flashing lights. These light sources add considerably to the overall light pollution.


A night time aerial view of a city reveals how much energy we waste by using unshielded lights. Any direct light sources that can be seen from above are contributing to a waste of energy and the precious resources that produce that energy.

Lincoln is fortunate to have some of the lowest electrical rates in the country. Summer rates are 6.5 cents per kilowatt-hour and winter rates are 5 cents. A national average is 8 cents. By reducing the amount of upward (wasted) light we can help to extend our overall energy pool. Since Lincoln is growing rapidly, this makes good economic sense.


This is the bane of astronomers world-wide. The combined output of all the lights in a city cause the sky to be washed out. Faint deep sky objects such as galaxies and nebula become impossible to see.

Sky glow is rapidly becoming worse. We must start now to encourage quality lighting. Reducing the upward shining light will help eliminate these light domes. Our children need to be able to see the stars. They are the ones with the eager questions and imaginations that will shape our future!


  1. Use the right amount of light, not overkill.
  2. Shield the light so that is goes down, not up or sideways.
  3. Use light timer controls whenever possible.
  4. Use LPS fixtures whenever possible because it is the most energy efficient and because its light can be filtered out with telescope filters.
  5. Avoid using round globe lights unless they are properly shielded.
  6. Be aware of quality lighting. Let people know when you see some good and attractive lighting arrangements.
  7. Educate other people about the adverse effects of inappropriate lighting.