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Science & Tech

How dark is the night?

  • Dec 05, 2012
  • 277 words
  • 2 minutes
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This is a composite assembled from data acquired by the Suomi NPP over nine days last April and 13 days in October. It took 312 orbits to get a clear shot of every part of Earth’s surface at night. Photo: NASA Earth Observatory
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This image is part of an animated view of the Earth at night assembled from data acquired by the Suomi NPP satellite. Photo: NASA Earth Observatory

NASA Earth Observatory has released dazzling images of the earth at night.

The latest images are composites assembled from data acquired by the Suomi National Polar-orbiting Partnership (Suomi NPP) satellite, which has orbited the Earth about 14 times a day since it lifted off in October 2011.

NASA Earth Observatory acquired the images using the “day-night band” of the Visible Infrared Imaging Radiometer Suite, which detects light in a range of wavelengths. “Smart” light sensors allow scientists to observe dim signals such as auroras, city lights, gas flares and reflected moonlight.

NASA’s Robert Simmon used data acquired over nine days in April and 13 days in October to create an animated view of the entire earth at night. Getting clear shots of all of Earth’s land surface took 312 orbits and 2.5 terabytes of data.

The resulting video (below) and images show the world lit up by city lights.

“Nothing tells us more about the spread of humans across the Earth than city lights,” said Chris Elvidge, head of the nighttime lights lab at the NOAA National Geophysical Data Center, in a feature article by NASA.


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