A New Messenger at Mercury Image

Craters with Dark Halos on Mercury The newest image released from the Messenger flyby of Mercury features two craters with dark halos surrounding them. The dark material was either generated by heat from the impact or was just below the surface and brought up by the impact. Either way, the assumption is that these are “newer” features since what ever process removed the dark halos from the rest of the craters — seemingly has not had the time needed to complete the process on these.