Astronomy Picture of the Day

Discover the cosmos! Each day a different image or photograph of our fascinating universe is featured, along with a brief explanation written by a professional astronomer.

2017 July 9
See Explanation.  Clicking on the picture will download
 the highest resolution version available.

Earth at Night
Image Credit : NASA, NOAA NGDC, Suomi-NPP, Earth Observatory,
Data and Processing: Chris Elvidge and Robert Simmon

Explanation: Can you find your favorite country or city? Surprisingly, on this world-wide nightscape, city lights make this task quite possible. Human-made lights highlight particularly developed or populated areas of the Earth's surface, including the seaboards of Europe, the eastern United States, and Japan. Many large cities are located near rivers or oceans so that they can exchange goods cheaply by boat. Particularly dark areas include the central parts of South America, Africa, Asia, and Australia. The featured composite was created from images that were collected during cloud-free periods in April and October 2012 by the Suomi-NPP satellite, from a polar orbit about 824 kilometers above the surface, using its Visible Infrared Imaging Radiometer Suite (VIIRS).

Tomorrow's picture: inner spiral


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