In this night Earth map the locations of permanent lights can be seen on the Earth's surface, along the daylight images provided by Google Maps.
The original image has been created by NASA using data from the Defense Meteorological Satellite Program (DMSP)'s Operational Linescan System (OLS), originally designed to view clouds by moonlight.
It has been necessary to convert NASA's image to the projection used by Google Maps, because originally was different, and the images didn't match. The final map consists of 87.970 images.
The brightest areas of the Earth are the most urbanized, but not necessarily the most populated (compare western Europe with China and India). Cities tend to grow along coastlines and transportation networks. The United States interstate highway system appears as a lattice connecting the brighter dots of city centers. In Russia, the Trans-Siberian railroad is 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 another bright thread through an otherwise dark region.
Some regions remain thinly populated and unlit. Antarctica is entirely dark. The interior jungles of Africa and South America are mostly dark. Deserts in Africa, Arabia, Australia, Mongolia, and the United States are poorly lit as well (except along the coast and rivers), along with the boreal forests of Canada and Russia, and the great mountains of the Himalaya.
The detailed images of the cities were taken by astronauts aboard the International Space Station. These have been obtained from the Image Science and Analysis Laboratory, NASA-Johnson Space Center. "The Gateway to Astronaut Photography of Earth".
Further information can be obtained from the Earth Observatory article Bright Lights, Big City, and NASA's Visible Earth website.
A printed poster with the image above is available for purchase at The Freeman Institute.
To view Earth images in a 3D interface you can download for free Google Earth.
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