![]() ![]() Some communities are becoming aware of this problem and are putting forth efforts to minimize the hazy, orange skyglow. Natural skyglow can come from natural light sources, such as the Sun, the Moon, the stars, or auroras. These artificial skyglows cause the sky to be 5–10 times brighter in urban areas than a naturally dark sky that is unaffected by artificial light. It consists of light that is either emitted directly upward or reflected from the ground that is then scattered by dust and gas molecules in the atmosphere, producing a luminous background or light dome. Artificial skyglow is caused by the over-illumination of the sky from large city centres, shopping centres, or stadiums. It occurs from both natural and human-made sources. Skyglow is the illumination of the night sky or parts of it, resembling an orange " smog". Mexico City at night, showing skyglow bright enough to read a book outside Opinions vary on what color the light should be, but most agree on the description of "warm", which is considered more yellow or orange/amber than white. The International Dark-Sky Association certifies fixtures as dark sky friendly, and these will have the IDA Fixture Seal of Approval. Lights should be shielded on the top and sides so light doesn't go up to the sky and only used when needed (use motion detectors and only the wattage necessary). Flagstaff is a city of over 70,000, but because of their lighting, their skies are dark enough to see the Milky Way. The concept was started in the 1950s by the city of Flagstaff, Arizona. Dark-sky lighting ĭark-sky lighting is a concept very important to the dark-sky movement, as it greatly minimizes light pollution. A 2011 project is to establish "dark sky oasis" in suburban areas. The dark-sky movement encourages the use of full-cutoff fixtures that cast little or no light upward in public areas and generally to encourage communities to adopt lighting regulations. Light pollution has also been found to affect human circadian rhythms. This biological study of darkness is called scotobiology. The over-illumination of the night sky is affecting these organisms (especially birds). Nocturnal animals can be harmed by light pollution because they are biologically evolved to be dependent on an environment with a certain number of hours of uninterrupted daytime and nighttime. For similar reasons, astronomers in Arizona helped push the governor there to veto a bill in 2012 which would have lifted a ban on illuminated billboards. ![]() ![]() For example, the world-famous Palomar Observatory in California is threatened by sky-glow from the nearby city of Escondido and local businesses. The movement started with professional and amateur astronomers alarmed that nocturnal skyglow from urban areas was blotting out the sight of stars. Earth Hour and National Dark-Sky Week are two examples of such efforts. The advantages of reducing light pollution include an increased number of stars visible at night, reducing the effects of electric lighting on the environment, improving the well-being, health and safety of both people and wildlife, and cutting down on energy usage. The dark-sky movement is a campaign to reduce light pollution. ![]()
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