The Dark Mark
This image, taken with the Narrow Angle Camera (NAC), shows part of an unnamed crater in Mercury's southern hemisphere. The relatively smooth crater floor is likely to be volcanic material that flooded the crater some time after it formed. The dark material visible in the crater's ejecta blanket was excavated on impact and is known as low reflectance material or LRM, one of the major color-compositional units that has been identified on Mercury's surface in MESSENGER multispectral images.
Date acquired: December 16, 2012
Image Credit: NASA/Johns Hopkins University Applied Physics Laboratory/Carnegie Institution of Washington