|Diameter||143000 km, 11 x Earth's|
|Average Distance from Sun||778 x 106km = 5.203 AU|
|Colour||Orangey brown with white bands|
|Atmosphere||Hydrogen, ammonia and methane|
|Length of Day||10 hours|
|Length of Year||12 years|
|No. of Moons||16|
|Gravity||2.34 x Earth's|
Jupiter is the fifth planet from the Sun and is the first of the gas giants. It is the largest planet in the Solar System - so large that over 1300 Earths would fit inside it.
Jupiter is mainly made of a gas called hydrogen with ammonia and methane mixed in. These chemicals give the planet its brown and white stripes. On the surface of the planet is the Great Red Spot. This is a huge hurricane-like storm that has raged for hundreds of years. It is large enough to fit about 4 Earths inside it.
In 1994, pieces of a comet called Shoemaker-Levy 9 crashed into Jupiter. At least 21 pieces of the comet hit the planet, leaving marks on the surface that lasted for months. This was the first time anybody had ever seen a comet collide with a planet.
The pressure at the centre of Jupiter is about 4 million times the pressure at the surface of Earth. A human would be crushed to a tiny gooey mess on Jupiter.
Jupiter and four of its moons, called Ganymede, Europa, Callisto and Io can easily be seen through binoculars. They are called the Galilean moons because they were first seen by the astronomer Galileo. Jupiter also has very faint rings like Saturnís but they are made of much darker pieces of rock so they are harder to see.
Jupiterís moons are also very interesting. Io is very volcanic and the Galileo spacecraft took pictures of huge eruptions of molten rock from the Moon.
Europa is thought to have a water ocean underneath its ice surface, making it one of the most likely places to find life in the Solar System. Research is currently being carried out to find a way to cut through the thick ice and send a spacecraft into this ocean to try to find life.
Authors: Carolyn Brinkworth and Claire Thomas
Last updated: July 2001