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Satellite image of the eastern seaboard at night.
Eastern seaboard at night: the white areas indicate sky glow from poor lighting. Poor lighting not only washes out the splendor of the heavens but also reduces visibility at night, wastes energy, and disturbs wildlife. The harmful effects of light pollution are far-reaching. Image courtesy NOAA and the US Air Force

National Dark-Sky Week (NDSW) is an event, usually occurring in April, during which people in the United States are encouraged to turn out their unnecessary outdoor lights in order to temporarily reduce light pollution. Light pollution is a hazy blanket of light in the atmosphere caused by improper lighting fixtures which direct light up into the sky instead of down toward the ground. Not only does light pollution waste energy, but it also creates great problems for stargazers. This “blanket of light” causes the beauty of the night sky to fade, and if the problem of light pollution is not addressed now, we are destined to lose the beauty of the cosmos that have been a part of human civilization since its beginning.

National Dark-Sky Week occurs on the week of the new moon in April since a full moon increases the light pollution. Therefore, NDSW for 2009 will be from April 20 to April 26. Note: This is a change.

How will National Dark-Sky Week reduce light pollution, given that it only lasts a week and not everyone in the country will participate? The main goal of NDSW is to raise awareness about the harmful effects of light pollution. It is not possible for all of the light pollution in this region of the world to disappear. However, it is possible to make a small difference in the quality of the night sky and inspire us all to preserve the beauty of the sky. Another main goal of this event is to promote the use of better lighting systems that direct light toward the ground where it should be and not up into the sky.