The United States at night seen by Suomi NPP satellite

This image of the continental United States 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 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.

Image Credit: NASA Earth Observatory/NOAA NGDC
Explanation from: http://www.nasa.gov/mission_pages/NPP/news/earth-at-night.html