A faint double ring crater is seen at upper right in this picture of Mercury taken one hour and 40 minutes before NASA Mariner 10 second rendezvous with the planet Sept. 21, 1975
Double Ring Craters
A faint double ring crater is seen at upper right in this picture of Mercury taken one hour and 40 minutes before NASA Mariner 10 second rendezvous with the planet Sept. 21, 1975