Light pollution is the term used for excess artificial light or artificial light that is obtrusive. Light pollution, also known as luminous pollution or photopollution, is one of the reasons why stars are more easily seen in the night sky when you are away from large cities. It is easier to see the stars in rural areas since large amounts of artificial lights are not around to cause light pollution. Understandably, light pollution has negative affects on astronomy and star watching. Astronomers, both professional and amateur, can lose the ability to see certain constellations due to light pollution. Below is a description of the effects of Light Pollution in Astronomy.
Skyglow is specifically the part of light pollution that has a lot of affect on astronomy and star gazing. Skyglow is the scattering of light in the atmosphere, so the more light you are around the more light will be scattered in the atmosphere. This will obscure the night sky and make it more difficult to see the stars. Skyglow causes a reduction in the contrast between stars and galaxies against the sky itself. This means that it is harder to see objects that are fainter, like stars that are an extraordinary distance away.
Skyglow has caused astronomers to change where they have their telescopes located and to use filters to reduce the effects of light pollution. An increasing amount of telescopes are being built more remote areas. Remoter areas generally have less light so there is less light scattered in the atmosphere, so it is easier to get a clear look at the stars. Another thing that some astronomers have tried is using “nebula filters”. Nebula filters only allow certain wavelengths of light to come through that are commonly found in nebulae(interstellar clouds of dust). There are also “light pollution filters” that are used. These are designed to reduce, but not completely eliminate, light pollution by filtering out spectral lights that are normally emitted by sodium and mercury vapor lamps. This increases contrast and allows for better viewing of dim objects like galaxies, nebulae and individual stars. The problem with these light pollution reduction filters (LPR) is that they reduce the brightness of what the person using the telescope is looking at and limit the use of further magnification.
Another form of light pollution that affects light pollution is light trespass. This is where artificial light directly enters the tube. The light will then reflected through the tube until it reaches the eyepiece. This causes a glow over the field of vision, which reduces contrast. A remedy for this would be a light shield for a telescope. This would, as the name suggests, helps keep light from directly entering the telescope.
Light pollution can cause a lot of problems for astronomers so taking the steps to help reduce the affects of light pollution so you can better enjoy your viewing.
http://curious.astro.cornell.edu/question.php?number=194
http://www.starastronomy.org/light-pollution
