The Visible Infrared Imaging Radiometer Suite has a "day-night band" that can detect natural and man-made light with unprecedented resolution and clarity. It can resolve everything from the nocturnal glow of the atmosphere to the light of a single boat at sea. It can detect auroras, wildfires, the reflection of moon and star light off clouds and ice and the lights alongside highways. The sensor has six times better spatial resolution and 250 times better resolution of lighting levels than anything that came before it.
The VIIRS instrument works by scanning in 22 different wavelength bands. For each pixel, it uses a low-, medium- or high-gain mode to accurately depict the light from each source. Low-light signals are amplified and bright lights are kept from being over-saturated.
The data from the Suomi satellite is freely available to the public within hours, providing the first look at the Earth at night for most scientists. Previously, the U.S. Air Force had a suite of night-time satellites with low-light sensors, but the data wasn't nearly as good, was mostly classified, and was available only to a few scientists.
Below:
United States
This image is a composite of data taken by the VIIRS instrument aboard the Suomi NPP satellite in April and October 2012.
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