FACT ONE Jupiter has a liquid metal ocean (metallic hydrogen) at its centre, surrounded by thousands of kilometres of hydrogen and helium gas. FACT TWO Jupiter's famous Red Spot is in fact a storm the size of Earth that has raged for hundreds of years. FACT THREE Jupiter has a thin set of rings, hardly visible, even with telescopes, from Earth. FACT FOUR Jupiter is the vacuum cleaner of the Solar System. It sucks in comets, asteroids and meteorites which could be on a collision course for Earth. The comet, Shoemaker-Levy 9, was pulled apart by Jupiter's gravity and eventually collided with the planet in 1994. FACT FIVE Jupiter takes only 9 hours and 55 minutes to spin on its axis. This means a day on Jupiter is less than 10 hours long. Its fast rotation causes the planet to be squashed, being wider at the equator than from North to South. FACT SIX Jupiter is the planet with the strongest pull of gravity in the Solar System. If we were able to stand on the surface of Jupiter, we would weigh three times as much as we would weigh on Earth. The only other object in the Solar System with a stronger pull of gravity is the Sun. FACT SEVEN The mass of Jupiter is 318 greater than the mass of Earth. FACT EIGHT Jupiter's moon, Ganymede, is the biggest moon in the Solar System. FACT NINE If we were able to see Jupiter's radiation belt from Earth, Jupiter would appear as big as the Sun. FACT TENJupiter's gravity is used to catapult space-craft on deep space missions further away. This is how the Voyager missions of 1975 managed to succeed.