Planet Guide and Information - Mercury

Distance from Sun (average)
58 million km
4850 km
Length of day
176 days
Length of year
88 days
Mean surface temperature
350°C (day), -170°C (night)

Mercury is a small, rocky barren planet and has no atmosphere to sustain any kind of life. This is one of the reasons why the daytime and night-time temperatures are so extreme - no atmosphere to keep the Sun's energy at bay during the day or keep the warmth in at night. Mercury was first visited by mankind in the form of the Mariner 10 probe in 1974 - it provided the first close-up pictures of Mercury which showed a heavily-cratered surface, not unlike that of the Moon.