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North America at night. Black marble satellite image of North America at night. More densely populated areas are brighter. The nocturnal glow produced by the Earth's atmosphere is shown as well as man-made light on land and from ships at sea. Data acquired by the day-night band of the Visible Infrared Imaging Radiometer Suite (VIIRS) on board the NASA-NOAA Suomi National Polar-orbiting Partnership (NPP) satellite, over nine days in April 2012 and 13 days in October 2012. (KEYSTONE/SCIENCE PHOTO LIBRARY/NASA /SCIENCE PHOTO LIBRARY)