Astronomy And Light Pollution
by Kevin Brown : last updated: October 3, 2008Most astronomers I know, increasingly struggle with the effects of light pollution on their observations.
Nowadays, once dusk falls, so many artificial lights come on that the sky still seems illuminated.
Even when we reach the scientific definition of night-time darkness, called Nautical Twilight and defined as the Sun being more than 12 degrees of angle below the horizon, it just does not seem properly dark.
Millions of street lights, road lighting and security lights, usually coloured, make sure the sky glows in a yellow-orange hue.
Certainly if you live in a city or town, or even within a few miles of one, you will be affected. And the consequence for astronomers is that any objects other than the very brightest planets and stars get “drowned out” to the point of invisibility.
My actual home location is fairly dark, but when I occasionally visit a truly dark place and the sky is clear, the difference is astonishing. So many stars become visible, it’s as if space has been swapped for a different one!
Sometimes the problem is caused more by the type of lighting, than its sheer brightness. Older lighting technology, or poorly aimed lighting units, can scatter light all around, including upwards, even if the light is actually required down on the ground.
So if light pollution is upsetting your astronomy, what can you do?
Here are a few steps to consider.
1. Perhaps your main problem is with a very localised light source, such as the security lights of a nearby business premises, or even just one neighbour’s house? You could approach the people concerned. Then ask politely, if they would examine what changes could be made to their lighting.
2. Get a portable telescope. The modern Schmidt Cassegrain telescopes (SCT) pack a lot of capability into a small and highly portable package. With one of these, you can simply put it in the car and drive to a darker observing site, if you have one nearby that you can use.
3. Obtain special filters for reducing the effect of artificial light. These can work well if you are doing digital iamging observation.
4. Attend an organised star party. These are usually held where possible, in good dark sites.
5. Support the organisations that are lobbying Government to introduce legislation to control and reduce light pollution. It is possible that this issue may be taken up by the International Year Of Astronomy in 2009.
