Beyond the Asteroid Belt, we are out in the region of the giants.

Jupiter is nearly 800 million kilometres from the Sun (five times as far away as Earth). It is mainly made of hydrogen and helium gas, but it has a small rocky core. It is orbited by its own system of rocky and icy satellites - 60 of them at the last count.

Jupiter is the biggest planet in the Solar System. In fact, it's a kind of failed star - it is only just below the size that would have allowed it go through the process of star formation and start burning. Its diameter is 11 times that of Earth, and its mass is 320 times greater, with a proportionately greater gravitational pull. Imagine lifting a tin of beans on Earth. On Jupiter, lifting that tin of beans would feel like you were trying to lift a beefy rugby player weighing 100 kg (about 15 and a half stone).

So Jupiter acts as the Solar System's vacuum cleaner, hoovering up comets and asteroids if they get too close. This is a beneficial side-effect of the planet's enormous pull, protecting Earth from many potential hazards.

Jupiter is an impressive sight, with horizontal coloured stripes formed by belts of clouds swept around by winds blowing at up to 400 kilometres per hour. One very obvious feature is the Great Red Spot - a particularly wild storm, about as wide as Earth, which has been raging for at least 100 years.

	This is an extract from 'Planet patrol', chapter 2 of the Voyage in Space
	and Time booklet