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.