Solar System Exploration Division
Solar System Tour - Mercury



The closest planet to the Sun, Mercury orbits in only 88 Earth days. However, its rotation is so slow that a "day" on Mercury lasts twice as long as its year.

Global view of Mercury, as seen by MESSENGER.

Global view of Mercury, as seen by MESSENGER

Smallest of the inner terrestrial planets, Mercury has been geologically inactive for billions of years and its surface is peppered with craters of all sizes, including the Caloris Basin, one of the largest impact sites in the solar system. The surface temperatures range from -170 °C (-275 °F) on the night side to 450 °C (840 °F) on the day side.

Compositional variation in Caloris Basin.

Compositional variation in Caloris Basin

Fun Facts

  • The Sun can look 10 times larger from Mercury than it does from Earth

  • Mercury is the only other rocky planet besides the Earth with a global magnetic field

  • Mercury has the largest iron core relative to its size of any planet


Mariner 10: Flybys (1974 (2), 1975)

MESSENGER: Orbiter (2011 - )