Moon Mare and Montes . ... Marvelously detailed , especially along the terminator or shadow line between lunar night and day, this cropped version of the full mosaicked image shows the cratered north polar region (top) and the broad smooth Mare Imbrium . ... The long, graceful arc of the lunar Montes Apenninus (Apennine Mountains) in the lower portion of the image sweeps southward along the boundary of the mare toward the left and ends near the bright ray crater Copernicus at the picture's edge. ...