Tangential Craters within Ptolemaeus Crater
This image shows two small craters, just touching on their rims, in the much larger Ptolmaeus Crater, which is located in the Martian Southern hemisphere. These craters are called "tangential craters."
The more degraded and filled-in crater is approximately 3 kilometers in diameter, and there is an unusual feature near the center. A closeup shows the feature is approximately 76 meters wide and 164 meters long. This feature is also possibly a substantially oblique impact crater, but its origin remains unknown.
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 the California Institute of Technology in Pasadena, manages the Mars Reconnaissance Orbiter Project for NASA's Science Mission Directorate, Washington.