Title:[0877] Mercury's southern hemisphere (Mariner 10) Caption:A photomosaic of Mercury's southern hemisphere taken during Mariner 10's second flyby of Mercury in September 1974. Copyright: Credit:NASA

Title:[0878] Mariner 10's incoming view of Mercury Caption:A photomosaic of Mercury taken as Mariner 10 approached the planet on its first flyby in March 1974. Copyright: Credit:NASA

Title:[0879] Mariner 10's outgoing view of Mercury Caption:A photomosaic of Mercury taken as Mariner 10 left the planet after its first flyby in March 1974. Most of the smooth plains are concentrated on this side. Copyright: Credit:NASA

Title:[2019] Part of the Caloris basin on Mercury Caption:A photomosaic of part of the Caloris basin on Mercury from images taken by Mariner 10 in 1974. It is 1,300 km in diameter and one of the largest impact features in the solar system. The main ring of mountains rises 2 km above the basin floor. Copyright: Credit:NASA

Title:[0028] The southwestern quadrant of Mercury Caption:A close-up view of part of the surface of Mercury taken by Mariner 10 in 1974, showing many impact craters. Copyright: Credit:NASA