We speak about light pollution when the artificial lightings are so many and omnipresent that they damage the normal and desirable night darkness. It is from the XXth century that street lightings begin strongly to develop. The fog, the steam and the molecules of air transport the light, what leads to an almost permanent bright fog in town and in campaign.

The light pollution is a shape of pollution enough little evocated because when we compare it with the more classic pollutions: waste, urban smog, soiled waters....
It is not without consequences and maybe easily reduced.

For the astronomers and the astrophysicists, the blackness of the sky is essential in the observation and in the study of celestial objects of low luminosity. The important growth of the light pollution affects more and more the activities of search for the big monitoring centers, because the increase of the artificial luminosity of the sky produces an effect similar to that of a shrinkage of telescopes.

The buckle of stars is caused by the light artificially emitted towards the sky, either directly by lamps, or having been reflected about the ground. The light emitted towards the sky is made visible because of the reflection on airborne particles (dusts, sprays, humidity) or of the intrinsic distribution of the atmosphere.

The buckle of stars is one of the important consequences of the light pollution which disrupts the work of the astronomers and deprives the city-dwellers of the beauty of the starry sky and the night landscapes. Today, it is unfortunately necessary to go away in some hundred kilometers of urban areas to perceive well the Milky Way. Associations try to make actions to find a more black sky.