Mercury Facts

  • Mercury is the nearest planet to the Sun — during its orbit it is between 45.9 and 69.7 million km away.
  • Mercury is the fastest orbiting of all the planets, getting around the Sun in just 88 days.
  • Mercury takes 58.6 clays to rotate once, so a Mercury day lasts nearly 59 times as long as ours.
  • Temperatures on Mercury veer from -180°C at night to over 430°C during the day (enough to melt lead).
  • The crust and mantle are made largely of rock, but the core (75 percent of its diameter) is solid iron.
  • Mercury’s dusty surface is pocketed by craters made by space debris crashing into it.
  • With barely 20 percent of Earth’s mass, Mercury is so small that its gravity can only hold on to a very thin atmosphere of sodium vapor.
  • Mercury is so small that its core has cooled and become solid (unlike Earth’s). As this happened, Mercury shrank and its surface wrinkled like the skin of an old apple.
  • Craters on Mercury discovered by the USA’s Mariner space probe have names like Bach, Beethoven, Wagner, Shakespeare and Tolstoy.