Dark halo craters on Mercury

Dark halo craters on Mercury

Fig. 6.11 . Two of the larger craters in this MESSENGER image appear to have darkened crater rims and partial "halos" of dark material immediately surrounding them. The explosive impact that produced the dark-halo craters could have excavated darker subsurface material or melted part of the surface, splashing it across the surface where it re-solidified as dark material. (Courtesy of NASA/JHUAPL/CIW.)

Copyright 2010, Professor Kenneth R. Lang, Tufts University