Position - fifth from the sun

Distance from sun - (nearest) 741 million km (furthest) 816 million km (average) 779 million km

Minimum distance from Earth - 590 million km

Diameter - 142,800 km

Satellites - at least 16 but only four large ones - Ganymede (5300 km), Callisto, Io and Europa. The others are named Metis, Adrastea, Amalthea, Thebe, Leda, Himalia, Lysithea, Elara, Ananke, Carme, Pasiphae and Sinope.

Atmosphere - hydrogen and helium

Surface Temperature -150 ^oC

Length of Day (time taken to rotate once) - about 10 hours

Length of Year (time taken to go round the Sun) - 12 Earth years

Comments - Jupiter is as big as all the rest of the planets put together. It is a type of planet known as a gas giant - it is probably a failed star. It is made of the same gases as stars and it does not have a proper solid surface. At the core it is hotter than the sun at about 30,000 oC.

Major Features - Jupiter has recently been discovered to have a thin ring system, like Saturn, but this is much thinner and less spectacular than Saturn's. The surface of Jupiter is a pattern of orange, red and white stripes caused by differences in the atmosphere. The Great Red Spot is a huge storm which has been going on for hundreds of years.

Seeing Jupiter from Earth - At it's closest Jupiter is a very bright white "star" - only Venus is brighter. It is so big that the disc, and the four largest moons, can be seen with binoculars.

Getting There - Several probes have been sent to Jupiter in the last 30 years, including Pioneer and most importantly Voyager 1 and 2. Galileo was launched in 1995 and we now know a lot about Jupiter and it's moons. It takes five or six years for a probe from Earth to reach Jupiter.