The night side of Earth twinkles with light, and the first thing to stand out is the cities. "Nothing tells us more about the spread of humans across the Earth than city lights," asserts Chris Elvidge, a NOAA scientist who has studied them for 20 years.

This new global view and animation of Earth's city lights is a composite assembled from data acquired by the Suomi National Polar-orbiting Partnership (Suomi NPP) satellite. The data was acquired over nine days in April 2012 and thirteen days in October 2012. It took satellite 312 orbits and 2.5 terabytes of data to get a clear shot of every parcel of Earth's land surface and islands. This new data was then mapped over existing Blue Marble imagery of Earth to provide a realistic view of the planet.

The image was made possible by the satellite's "day-night band" of the Visible Infrared Imaging Radiometer Suite (VIIRS), which detects light in a range of wavelengths from green to near-infrared and uses filtering techniques to observe dim signals such as city lights, gas flares, auroras, wildfires and reflected moonlight.

Named for satellite meteorology pioneer Verner Suomi, NPP flies over any given point on Earth's surface twice each day at roughly 1:30 a.m. and 1:30 p.m. The polar-orbiting satellite flies 824 kilometers (512 miles) above the surface as it circles the planet 14 times a day. Data is sent once per orbit to a ground station in Svalbard, Norway, and continuously to local direct broadcast users around the world.

The mission is managed by NASA with operational support from NOAA and its Joint Polar Satellite System, which manages the satellite's ground system.

Credit: NASA Earth Observatory/NOAA NGDC

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