Only a few generations ago everyone could look up and see thousands of stars, now many of us cannot. This is because of light pollution. Light pollution is unwanted or excessive artificial light and is a form of wasted energy. It has an adverse effect on visual astronomy and astrophotography and degrades environmental quality.
According to the 2016 'World Atlas of Artificial Night Sky Brightness,' 80% of the world's human population lives under skyglow. In Europe and the USA 99% of people cannot experience a natural night!
Due to wasted energy, if we decreased light pollution, we could decrease energy utilisation and therefore decrease the use of fossil fuels with a positive side effect of reduction in air pollution and negative climate change.
Light pollution severely reduces the visibility of stars and other celestial bodies due to 'skyglow' or the upward-directed light emanating from poorly designed or directed lights. This light is scattered and reflected by particles in the atmosphere. We are all affected by the reduction in the beauty of the night sky, but it also affects the quality of life of many by causing discomfort and distraction from neighbour's, and the bright and misdirected streetlights.
Migratory birds use the light from stars and the Moon to assist their navigation, and our light pollution can disorient them. Light pollution is thought to be one of the contributory factors in the dramatic decline of certain migratory bird populations over the past few decades and this should concern all of us. It also affects insects and has been shown to affect moth caterpillars, with even worse effects evident with the latest trend of fitting streetlights with LEDs (light-emitting diodes).
Skyglow levels can be calculated as a function of population and distance from the observer. Levels 10% over natural background levels signify significant sky degradation, and even lights from a town with only 3000 people cause significant night sky degradation for an observer 6 miles (10km) away.
For astronomy, we use the Bortle scale to grade light pollution, although there are a number of other ways to measure how much light pollution affects a given location (eg SQM, NELM).
You can find the light pollution for a particular site using this link:
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