Jupiter is the fifth planet from the Sun, and, with an average diameter of 143,884 kilometres (89,369 miles) the largest planet in the Solar System. Large enough to contain more than 1300 Earths inside it, Jupiter is more massive than all the other planets combined. Along with Saturn, Uranus and Neptune, it is one of the four gas giants. Apart from its relatively small rocky core, Jupiter is almost entirely made up of hydrogen and helium, with no solid surface at all. Its rocky core is probably surrounded by a liquid ocean of hydrogen.

Atmosphere

The colourful patterns of red, white, blue, brown and yellow on Jupiter’s surface do not make up any fabulous landscape, but are produced by Jupiter’s swirling atmosphere. The colours themselves come from small amounts of sulphur and phosphorus present in the atmospheric gases. The planet is striped by different coloured “zones” (the lighter bands) and “belts” (the darker bands). Storms rage continuously on Jupiter. The planet's most famous feature, the Great Red Spot, is just such a storm.

The Great Red Spot is a storm that has been raging for at least 300 years. It is twice the size of Earth. The vast oval of swirling clouds is about 16,350 kilometres (10,100 miles) across, and lies about 40 kilometres (25 miles) above the level of most of the other clouds. It is uncertain why the spot is red. One possibility is that cosmic rays or ultraviolet light from the Sun may react with certain chemicals in Jupiter's outer atmosphere to create the deep red colour.

The spot‘s topmost clouds turn in an anticlockwise direction, taking about six days to make one full turn. This sequence shows turbulent air currents flowing past the Spot, right to left on its northern side, left to right on its southern side. The spot acts as an obstruction to the violent winds that blow round the planet. White ovals, like the one visible here, are similar, but smaller, storms.

Rings and moons

Jupiter has faint rings consisting of dark grains of dust. There is an inner ring (called the halo) made up of particles, a main ring and a faint outer ring.

​​​​​​​Jupiter's four largest moons are, in order of size, Ganymede, Callisto, Io and Europa. They are named the Galilean moons, after the Italian scientist Galileo, who discovered them using a telescope in 1610. All four are larger than the dwarf planet Pluto. Looking like a cracked egg, Europa’s surface may consist of ice sheets that are continually melting and re-solidifying. Below them there could be a warm ocean of water, where it is possible there may even be life-forms.

Composition

Jupiter is mostly made of hydrogen (about 90% of its volume) and helium, but only a small part of the hydrogen is found in its gaseous form. Surrounding its small rocky core (actually twice the size of Earth) is a thick layer of hydrogen that is so dense it is like a metal. Above that is a layer of liquid hydrogen, then a thick atmosphere of gaseous hydrogen and helium. Its clouds are made of ammonia, methane and water ice.

Factfile

Average diameter: 142,984 km (88,846 miles)

Mass: 318 (Earth = 1)

Average density: 1.3 (water = 1)

Surface gravity 2.64 (Earth = 1)

Day: 9.8 hours

Year: 11.8 years

Average speed in orbit: 13 km/sec (8 miles/sec)

Average distance from the Sun: 778 million km (483 million miles)

Temperature (at cloud tops): -150°C (-238°F)

Atmosphere: hydrogen, helium

Number of known moons: 115 (as of April 2026)

Name: the Roman king of the gods