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Jupiter

Jupiter is the largest planet in the Solar System. It weighs as much as 318 whole Earths (twice the mass of all the other planets combined!). Like most planets, Jupiter is a naked-eye object, known since antiquity. Galileo used a telescope to discover moons of planets. It is made of  gasses and ices with a little rock and is believed to have a solid core surrounded by liquid metallic hydrogen. This liquid metal gives the planet its magnetic field. Despite its distance from the Sun, Jupiter radiates more heat than it receives, a fact attributable to the huge mass of the planet and the movements of its gasses.

Jupiter’s most notable features are its giant red spot and its overall colours. The Great Red Spot is a huge spinning mass of gas which rotates slowly round the planet’s Southern Hemisphere. It is the size of 2 Earths. The belts and bands of colour are caused by varying winds pushing gasses containing different allotropes of sulfur across the atmosphere.

Not long ago it was believed that Jupiter had no rings, but recently a thin system of rings has been discovered around the planet. Jupiter’s rings are believed to be made of small rocks and dust but, unlike other ring systems, they contain no ice. 

In 1994 Jupiter was hit by the fragments of the Shoemaker-Levy 9 comet which exploded into its Southern Hemisphere. The blemishes from this are still visible. It is events like this which replenish the dust and matter in Jupiter’s ring.

Diameter

143, 000 km

Mass

1.9 × 1027kg

Mean Distance from sun

778,330,000 km

Mean Density

1.33 g/cm3

Rotational Period

0.4 Earth days

Orbital Period

4333 Earth days

Mean Orbital Velocity

13 km/s

Atmosphere

90% Hydrogen, 10% Helium

Average Surface Temperature

-121°C

Equatorial Surface Gravity

22.88 m/s2