On December 5, 2012, NASA released a nighttime view of Earth called Black Marble during an annual meeting of earth scientists held by the American Geophysical Union in San Francisco. The images display all the human and natural matter that glows and can be sensed from space.
The data was acquired by the Suomi NPP satellite in April and October 2012 and then mapped over existing Blue Marble imagery of Earth to provide a realistic view of the planet. The Suomi NPP satellite completed 312 orbits and gathered 2.5 terabytes of data to get a clear shot of every parcel of the Earth’s land surface. Named for satellite meteorology pioneer Verner Suomi, the satellite flies over any given point on Earth’s surface twice each day and flies 512 miles above the surface in a polar orbit.
According to NASA, the nighttime views were made possible by the new satellite’s “day-night band” of the Visible Infrared Imaging Radiometer Suite. The so-called VIIRS 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. Auroras, fires, and other stray light have been removed in the case of the Black Marble images to emphasize the city lights. The NASA stated that nighttime images can be used for numerous purposes:
Social scientists and demographers have used night lights to model the spatial distribution of economic activity, of constructed surfaces, and of populations. Planners and environmental groups have used maps of lights to select sites for astronomical observatories and to monitor human development around parks and wildlife refuges. Electric power companies, emergency managers, and news media turn to night lights to observe blackouts.