Light Pollution

From Slackerpedia Galactica

Salt Lake City from the air Photo by Brian Jolley

1 Introduction
2 Light Pollution and Astronomy
3 Workarounds
4 External Links

Introduction

Light pollution is the light that escapes upwards or side-wards from means of illumination at night. The normal usage is light that causes the viewer's eyes to be desensitised to the light from the stars and other cosmic sources. However, 'trespass' can also occur when a neighbour's light gets into another's property when it is not wanted.

Unwanted light can disrupt ecosystems, cause adverse health effects, obscure stars to city dwellers, interfere with astronomical observatories, waste energy, and fade curtains (the same as daylight saving.)

Light Pollution and Astronomy

Light pollution is the junk that visible light photons have the nerve to throw into the sky. It is the natural predator of the dark sky. Light pollution is noticeable in densely populated areas that have bright, uncovered lights. If you can't see the stars at night because the neighbor's porch light is shining in your eyes, that's light pollution. They may say it's for safety, but they aren't safer, and you can't see the stars.

Light pollution annoys astronomers and robs much of Earth's population of the opportunity to enjoy the night sky. Light pollution is also a threat to wildlife. All species of sea turtles native to Florida waters are listed as either threatened or endangered, and according to the Florida Fish and Wildlife Conservation Commission, light pollution is a major contributing factor. On top of this, light pollution threatens our own health. Recent studies have linked light pollution to certain forms of cancer including breast cancer.

If light pollution provided some benefit to society, we could debate the pros and cons. However, light pollution provides no benefits whatsoever. The only possibly beneficiary would be the utility companies. Far too much light is wasted into space rather than directed where it can be useful. This wastes incredible amounts of energy. However, dark energy's role in light pollution is unknown.

The International Dark-Sky Association (IDA) promotes awareness and conservation of dark skies.

Let's stamp out Light Pollution in our lifetimes. As the IDA says, Carpe noctem—seize the night!

Workarounds

So let's say you bring your telescope to a grocery store parking lot, complete with flood lights to show the unwashed masses (which is alot of fun). Sure, you can show them the Sun, the Moon and some planets. But can you show them a Faint Fuzzy? It turns out that many nebulae can be seen under these conditions. Narrow band filters, such as Oxygen 3, will show many such objects, such as M42 the Great Orion Nebula, and M16, the Eagle Nebula. Narrow band filters do not pass the wavelengths used in most lighting. So, the sky glow turns black, allowing the Faint Fuzzy to show up with good contrast. Oxygen 3 filters work with 6 inch (150 mm) or larger telescopes. Since they reject most light, it helps to have a little aperture fever.