The Mariner 10 spacecraft took numerous images of Mercury during 1974 and 1975 that provided the first close-up look at the planet nearest the Sun. The cratered surface looks much like that of the Moon but there are some important difference between the surfaces of the two objects. The craters on Mercury are shallower than lunar craters of equivalent size due to the stronger mercurian gravitational field. The albedo (the reflected brightness) of Mercury is considerably higher than that of the Moon, with the dark regions of Mercury having about the same albedo as the bright areas of the Moon.
Mosaic of 18 images taken by Mariner 10 on March 29, 1974, about 6 hours before closest approach to Mercury (see Fig. 18 of Davies et al., 1976).