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New Wallpaper: Earth at Night
By SPACE.com Staff
posted: 07:00 am ET
02 January 2001
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earth_at_night_010102 Things on Earth are getting brighter. Satellites are increasingly being used to study the effects of human activity on ecosystems and climate. And one offshoot of this effort has yielded a worldwide map of urban lights, in which cities, coastlines and even the U.S. Interstate Highway System are visible. The image shows a high degree of urbanization worldwide. The percentage of the U.S. population living in urban areas, for example, rose from less than 50 percent in decades past to 73 percent in 1995, according to the U.S. Census Bureau. The image was created by NASA's Craig Mayhew and Robert Simmon, based on data from the Defense Meteorological Satellite Program. The effort dates back to the mid 1990s. Working with others, Marc Imhoff, a biologist at NASAs Goddard Space Flight Center, collected satellite images, pasted them together and used computers to massage the images into meaningful representations of urban areas. [inset] The image clearly shows coastlines and transportation networks -- where cities tend to grow, the researchers say. In Russia, the Trans-Siberian railroad shows up in the image as a thin line stretching from Moscow through the center of Asia to Vladivostok. The Nile River, from the Aswan Dam to the Mediterranean Sea, is a bright thread through an otherwise dark region. Antarctica appears to be entirely dark. The interior jungles of Africa and South America are mostly dark, but lights are beginning to show up there, researchers noted. Deserts in Africa, Arabia, Australia, Mongolia and the United States are poorly lit as well, along with the boreal forests of Canada and Russia, and the great mountains of the Himalayas. Click here to download Earth at Night as wallpaper for your computer.
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