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The crater at the center of this image contains a large, nearly circular
pit crater, identified with the white arrow. Multiple examples of pit
craters (PIA10186) have been observed on Mercury on the floors
of impact craters, leading to the name pit-floor craters for the impact
structures that host these features. Unlike impact craters, pit craters
are rimless, often irregularly shaped, steep-sided, and display no
associated ejecta or lava flows. These pit craters are thought to be
evidence of shallow volcanic activity and may have formed when retreating
magma caused an unsupported area of the surface to collapse, creating a
pit. Pit-floor craters may provide an indication of internal igneous
processes where other evidence of volcanic processes is absent or
ambiguous. The discovery of multiple pit-floor craters augments a growing
body of evidence that volcanic activity has been a widespread process in
the geologic evolution of Mercury's crust.
Date Acquired: January 14, 2008
Instrument: Narrow Angle Camera (NAC) of the Mercury Dual Imaging System (MDIS)
Resolution: 510 meters/pixel (0.32 miles/pixel)
Scale: The central impact crater with the pit crater on its floor is 102 kilometers (63 miles) in diameter.
Location: 35.5°N, 249.1°E
Projection: This image is an orthographic reprojection created from NAC images
taken as MESSENGER approached Mercury during its first flyby.
These images are from MESSENGER, a NASA Discovery mission to conduct the
first orbital study of the innermost planet, Mercury. For information
regarding the use of images, see the MESSENGER image use policy.