Light pollution and astronomy

Abstract

All astronomical observations are essentially an observation of contrast. Any stray light causes a veil, reducing all contrasts. Sky glow is disability glare. This hold for all sources. Diffraction makes even point sources into surface sources. The decrease in the limiting magnitude as a result of the veiling luminance is expressed in the ‘sky glow formula’. Over the years, many measurements of light pollution have been made regarding the distribution in place and time, both local and regional. Satellite observations made it possible that in 2001 ‘The First World Atlas of the Artificial Night Sky Brightness’ was published. It is found that about two-thirds of the world population is subject to light pollution. For 25% of the world population, only the brighter stars can be seen, but not the Milky Way. For 85% of the population in the Netherlands, the artificial light exceeds that of the full moon, and in only 3% of the area of the country, the artificial brightness is less than the natural brightness. The Atlas is based on measurements that are made by the Defense Meteorological Satellite Program (DMSP). In spite of considerable efforts to avoid it, sky glow did increase considerably on a global scale over the last few years. At present, it seems safe to expect that the levels of light pollution at most locations in the world are increasing and that they will go on increasing for the foreseeable future. A rate of increase is difficult to guess but it might seem that 3% per year will not be too far off. It should be noted that 3% per year means a doubling in 23 years.KeywordsAstronomical ObservationLuminous FluxLight PollutionUpward FluxDefense Meteorological Satellite ProgramThese keywords were added by machine and not by the authors. This process is experimental and the keywords may be updated as the learning algorithm improves.