NASA - Mars Reconnaissance Orbiter (MRO) logo.
This image from NASA's Mars Reconnaissance Orbiter (MRO) shows the location with the most impressive known gully activity in Mars' northern hemisphere. Gullies are active in the winter due to carbon dioxide frost, but northern winters are shorter and warmer than southern winters, so there is less frost and less gully activity.
An enhanced-color image cutout shows recent gullies with bright colors.
The map is projected here at a scale of 50 centimeters (19.7 inches) per pixel. [The original image scale is 61.5 centimeters (24.2 inches) per pixel (with 2 x 2 binning); objects on the order of 185 centimeters (72.8 inches) across are resolved.] North is up
The University of Arizona, Tucson, operates HiRISE, which was built by Ball Aerospace & Technologies Corp., Boulder, Colo. NASA's Jet Propulsion Laboratory, a division of Caltech in Pasadena, California, manages the Mars Reconnaissance Orbiter Project for NASA's Science Mission Directorate, Washington.
Mars Reconnaissance Orbiter (MRO): http://www.nasa.gov/mission_pages/MRO/main/index.html
Image, Text, Credits: NASA/Tony Greicius/JPL-Caltech/Univ. of Arizona.
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