A century and a quarter later, electric light turns night into day around the globe. In the first world atlas of artificial night-sky brightness, released in 2001 by the Italian astronomer Pierantonio Cinzano and based on high-resolution satellite data, the heavily developed urban corridors of Japan, Western Europe, and the United States blaze like amusement parks. We flood the heavens with so much artificial light that nearly two-thirds of the worlds people can no longer see the Milky Way. On a clear, dark night far from light-polluted skies, roughly 2,500 celestial points of light can be discerned by the naked eye. For people living in the suburbs of New York, that number dwindles to 250; residents of Manhattan are lucky to see 15. Moreover, as the stars fade from view, a growing body of research suggests that excessive exposure to artificial night light can alter basic biological rhythms in animals, change predator-prey relationships, and even trigger deadly hormonal imbalances in humans.
http://www.discover.com/July_03/featlights.html
