Mercury: Images of a Violent Planet

Mercury, the closest planet to the sun, remains the most mysterious of the solar system's inner planets. The only spacecraft to explore Mercury close-up was Mariner 10, which executed three flybys of Mercury in 1974 and 1975, surveying approximately 45 percent of its surface. Its highest resolution photographs recorded features approximately a mile across. A reprocessing of the Mariner 10 data has resulted in this dramatic mosaic. (NASA)