Update: This crater containing interesting dark material was given the name Hemingway in July 2009.

Date Acquired: October 6, 2008
Image Mission Elapsed Time (MET): 131771988
Instrument: Narrow Angle Camera (NAC) of the Mercury Dual Imaging System (MDIS)
Resolution: 260 meters/pixel (0.16 miles/pixel)
Scale: This image is about 270 kilometers (170 miles) across
Spacecraft Altitude: 10,100 kilometers (6,300 miles)

Of Interest: The crater in the lower right-hand corner of this image has a patch of very dark material located near its center. The region of this image has been seen only with the Sun high overhead in the sky. Such lighting conditions are good for recognizing color differences of rocks but not well suited for ascertaining the topography of surface features from shadows. The shape of the surface in this area is difficult to resolve given the lighting angle, but the dark patch is not in shadow. Dark surfaces have also been seen on other regions of Mercury, including this dark halo imaged during the second Mercury flyby and near such named craters as Nawahi, Atget, and Basho seen during MESSENGER's first Mercury encounter. The example here is particularly striking, however, and from this NAC image the material may appear even darker than in other example areas. The dark color is likely due to rocks that have a different mineralogical composition from that of the surrounding surface. Understanding why these patches of dark rocks are found on Mercury's surface is a question of interest to the MESSENGER Science Team. The right edge of the image here aligns with this previously released NAC image, where other dark surface material, as well as patches of light-colored rocks, can be seen.

Credit: NASA/Johns Hopkins University Applied Physics Laboratory/Carnegie Institution of Washington

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