America at Night

NASA image acquired April 18 - October 23, 2012

This image of the United States of America at night is a composite assembled from data acquired by the Suomi NPP satellite in April and October 2012. The image was made possible by the new 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.

“Nighttime light is the most interesting data that I’ve had a chance to work with,” says Chris Elvidge, who leads the Earth Observation Group at NOAA’s National Geophysical Data Center. “I’m always amazed at what city light images show us about human activity.” His research group has been approached by scientists seeking to model the distribution of carbon dioxide emissions from fossil fuels and to monitor the activity of commercial fishing fleets. Biologists have examined how urban growth has fragmented animal habitat. Elvidge even learned once of a study of dictatorships in various parts of the world and how nighttime lights had a tendency to expand in the dictator’s hometown or province.

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 p.m. The polar-orbiting satellite flies 824 kilometers (512 miles) above the surface, sending its data once per orbit to a ground station in Svalbard, Norway, and continuously to local direct broadcast users distributed around the world. Suomi NPP is managed by NASA with operational support from NOAA and its Joint Polar Satellite System, which manages the satellite's ground system.