Light pollution

Light pollution
written by Mara Manduchi
Bachelors in Astronomy-University of Bologna,Italy
Teacher of Physics and Mathematics

With the term “light pollution” we intend an alteration of the natural ambient light levels in the night environment produced by artificial light.
The size of pollution level, that varies from place to place, represents one of the rapidly increasing alteration of natural environment.
The major negative effect is the growth of night sky brightness, responsible of the loss of starred sky visibility. Professional and amateur astronomers are suffering greatly for the adverse effects of night sky observation: due to light pollution, optical instruments potentiality cannot be used at all.
Light pollution is a serious problem not only for scientists and astronomers but for common people as well. The whitish fog surrounding Earth produces a loss of perception of the Universe depriving people of a contact with nature. Starred sky observation, that has always had strong influence on human thought and culture, both humanistic and scientific (art, religion, philosophy, literature, physic, astrophysics), is precluded to an increasing part of world population.
It has been calculated that about two-thirds of the world population and 99 per cent of the population in the United States (excluding Alaska and Hawaii) and European Union live in areas where the night sky is above the threshold set for polluted status. Assuming average eye functionality, about one-fifth of the World population, more than two-thirds of the United States population and more than one half of the European Union population have already lost naked eye visibility of the Milky Way (1)
Many impacts on the natural environment due to light pollution are shown by a large number of studies and reports: alterations of life and hunt custom in animals, disturbances associated with animal reproduction and migration, alterations of circadian rhythm, alteration of plants photosynthesis process and photoperiodism.
Not to underestimate the importance of saving energy reducing the use of not necessary light sources and developing eco-sustainable illumination technology. Energy waste is in fact both an economic and environmental damage.
To get an impression of light pollution entity in Europe you can see the “loss of stellar visibility in Europe map” in http://www.savethenight.eu/Map.html\ which show the loss of capability of population to see stare in Europe, and the "Lights in Europe" map in http://www.savethenight.eu/Lights%20in%20Europe.html that show radiance of the Heart surface mesaured by satellites.


References

http://www.lightpollution.it
http://www.savethenight.eu

(1) “The first world atlas of the artificial night sky brightness.” P. Cinzano, F. Falchi, C.D. Elvidge - Monthly Notices of the Royal Astronomical Society, 328, 689-707 (2001)