We often think of Earth as a 'blue marble' floating in the vacuum of space, but a new series of images released by NASA show it as a 'black marble' -- with the outlines of cities aglow at nighttime.
The new global view 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 13 days in October 2012.
It took the satellite 312 orbits and 2.5 terabytes of data to get a clear shot of every parcel of Earth's land surface and islands. The new data was then mapped over existing Blue Marble imagery of Earth to provide a realistic view of the planet.