When trying to view distant stars and or other phenomenon they are so far away that the light from them which reaches us is very small so prolonged exposures are necessary to capture those images...near a city which has many lights the light from the city is greater than the light from distant stars etc....thus you see fewer stars when in the city than when in the rural countryside.
Light pollution is how they describe that effect...that's the reason they build observatories on mountain tops or in very rural areas to get above the light pollution.
2007-01-26 08:21:53
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answer #2
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answered by thefoster1 1
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If you are in a big city on a cloudless night, you won't be able to see as many stars as you would if you were in a remote area. Light pollution is simply a large amount of light that blocks the view of space from someone observing on earth. Observatory telescopes are usually found in remote areas to avoid light pollution.
2007-01-26 07:41:26
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answer #3
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answered by NeonBlue 3
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At night, if you live near a big city, you will be able to see a dim yellow haze near the horizon. What you see is not sunlight. The haze is caused by the thousands of bright lights illuminating the pollution in the air, forming a glowing cloud
Satellite image of light pollution in the U.S.
http://users.zoominternet.net/~matto/M.C.A.S/lightpollution.gif
2007-01-26 08:04:50
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answer #4
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answered by Ammy 6
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Light pollution is excess or obtrusive light created by humans. Among other effects, it can cause adverse health effects, obscures stars to city dwellers, interferes with astronomical observatories, wastes energy and disrupts ecosystems. Light pollution can be construed to have two main branches: (a) annoying light that intrudes on an otherwise natural or low light setting and (b) excessive light, generally indoors, that leads to worker discomfort and adverse health effects. Since the early 1980s, a global dark-sky movement has emerged, with concerned people campaigning to reduce the amount of light pollution.Light pollution is a side effect of industrial civilization. It comes from sources such as building exterior and interior lighting, advertising, commercial properties, offices, factories, streetlights, and lit sporting venues. It is most severe in the highly industrialized, densely populated areas of the United States, Europe, and Japan, but even relatively small amounts of light can be noticed and create problems.With recent advances in private spaceflight, the prospect of space-based orbiting billboards appearing in the near future has provoked concern that such objects may become another form of light pollution. With this in mind, the United States Federal Aviation Administration sought permission, in May 2005, to enforce a law prohibiting "obtrusive" advertising in earth orbit . Similar intentions are yet to be expressed by authorities in most other countries, however."Light pollution" (also known as photopollution, luminous pollution) refers to light that people find annoying, wasteful or harmful. It also does a lot of damage to the environment and health, as do other forms of pollution such as air pollution, noise pollution, water pollution and soil contamination.Many people wish to reduce light pollution. However, it is unrealistic to expect populations to significantly reduce their light pollution, due to industrial society's economic reliance on man-made light. Detractors posit that light pollution is a problem similar to traditional forms of pollution. Energy conservation advocates contend that light pollution must be addressed by changing the habits of society, so that lighting is used more efficiently, with less waste and less creation of unwanted or unneeded illumination. The case against light pollution is strengthened by a range of studies on health effects, suggesting that excess light may induce loss in visual acuity, hypertension, headaches and increased incidence of carcinoma.Several industry groups also recognize light pollution as an important issue. For example, the Institution of Lighting Engineers in the United Kingdom provides information for its members about light pollution, the problems it causes, and how to reduce its impacts.Since not everyone is irritated by the same lighting sources, it is common for one person's light "pollution" to be light that is desirable for another. One example of this is found in advertising, when an advertiser wishes for particular lights to be bright and visible, even though others find them annoying. Other types of light pollution are more certain. For instance, light that accidentally crosses a property boundary and annoys a neighbor is generally wasted and pollutive light.Disputes are still common when deciding appropriate action, and differences in opinion over what light is considered reasonable, and who should be responsible, mean that negotiation must sometimes take place between parties. Where objective measurement is desired, light levels can be quantified by field measurement or mathematical modeling, with results typically displayed as an isophote map or light contour map. Authorities have also taken a variety of measures for dealing with light pollution, depending on the interests, beliefs and understandings of the society involved. Measures range from doing nothing at all, to implementing strict laws and regulations about how lights may be installed and used.
2007-01-26 07:26:43
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answer #8
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answered by zara ahmed 4
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