JUPITER KING OF PLANETS

Blast off with BBC Sky At Night's Ezzy Pearson as she takes you on a voyage to explore the largest planet in our solar system.

Large enough to fit every other planet inside, it’s no surprise Jupiter holds the title of “King of the Solar System”.

Last year the European Space Agency sent the Jupiter Icy Moons Explorer (JUICE for short) on the long journey towards the planet, and this October NASA will launch the Europa Clipper to join it on its way. The trip will take five and a half years, because Jupiter lies around 484 million miles from the Sun – five times further away than Earth.

With its century-long storms, deadly radiation and a glittering assortment of moons, the solar system’s largest planet is a fascinating – and deadly – place to visit.

A giant gassy ball

Jupiter is around 86,881 miles wide and it contains more than twice as much mass as every other planet put together. The more material a planet has, the stronger its gravity. So, if you stood on a set of scales on Jupiter you would be nearly two and a half times heavier than you are on Earth. You wouldn’t be any bigger – the planet is just pulling down on you more.

You’d have a tough time standing anywhere on Jupiter though, because it’s a gas giant. The solar system’s inner planets – Mercury, Venus, Earth and Mars – are mostly made of rock, but Jupiter is entirely made of its atmosphere.

The planet is about 90% hydrogen gas, the lightest known element in the universe. Most of the remaining 10% is helium, the gas used to fill balloons so they float. There are also trace amounts of other chemicals, such as water and ammonia (which is used on Earth to make plant fertilisers), which form Jupiter’s clouds.

Jupiter’s outer atmosphere is about 30 miles thick. Below this, there is a layer of hydrogen and helium 13,000 miles thick, which changes from gas to liquid as the depth and pressure increase. Under this lies a deep sea – 25,000 miles deep – of liquid metallic hydrogen.