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An Intriguing Dark Halo
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An Intriguing Dark Halo
Release Date: October 9, 2008
Topics: Craters with Dark Material, Mercury Flyby 2, NAC



Update: This crater featuring dark material was given the name Derain in July 2009.

Date Acquired: October 6, 2008
Image Mission Elapsed Time (MET): 131774051
Instrument: Narrow Angle Camera (NAC) of the Mercury Dual Imaging System (MDIS)
Resolution: 540 meters/pixel (0.34 miles/pixel) on the left side of the image
Scale: This image is about 550 kilometers tall (340 miles)
Spacecraft Altitude: 21,200 kilometers (13,100 miles)

Of Interest: A crater discovered in the newly imaged portion of Mercuryís surface during MESSENGERís second Mercury flyby has uncommonly dark material within and surrounding the crater. The material is darker than the neighboring terrain such that this crater with a diameter of 180 kilometers (110 miles) is easily identified even in a distant global image of Mercury; it is located just south of the equator near the limb of the planet in this previously released Wide Angle Camera (WAC) image. The dark halo may be material with a mineralogical composition different from the majority of Mercuryís visible surface. Craters with similar dark material on or near their rims were seen on the floor of the Caloris basin during MESSENGERís first flyby. Images acquired though the 11 different narrow-band color filters of the WAC during MESSENGERís second flyby will be crucial to an understanding of the nature of this newly seen, unusual feature.

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


For information regarding the use of MESSENGER images, see the image use policy.


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