Much of what we know about Jupiter was discovered by two spacecraft - NASA's Voyager in 1979 and Galileo, which reached the planet in 2000.
Jupiter is the largest planet in the Solar System and the first of the gas giants. These are planets that were formed by the lighter elements in the outer reaches of the Solar System. Jupiter's radius is more than eleven times that of Earth. It also spins extremely fast on its axis, completing a revolution in less than 10 hours. Seen from Earth, the planet has a distinctive, banded appearance produced by its complex atmosphere.
Its dominant feature is The Great Red Spot, a huge storm system that has raged for centuries and would engulf our entire planet. It is so big that it has been visible in Jupiter's atmosphere ever since the planet was discovered.
Jupiter also has four large moons. One of these, Ganymede, is bigger than the planet Mercury and is the largest moon in the Solar System. Jupiter also has 15 smaller moons, all attracted by its powerful gravitational force.
