Planets

MERCURY

Mercury is the closest planet to the sun. The ancient symbol for Mercury is still used by astronomers.

Distance from sun: Shortest--46 million kilometres; Greatest--69.8 million kilometres;     Mean--57.9 million kilometres.

Distance from the earth: Shortest--91.7 million kilometres; Greatest--218.9 million kilometres.

Diameter: 4,878 kilometres.

Density: 5.44 grams per cubic centimetre.

Length of year: 88 earth-days.

Rotation period: 59 earth-days.

Temperature: -173 to 427 degrees C.

Atmosphere: Helium, hydrogen, oxygen.

Number of satellites: None.