Jupiter, the largest planet, named after the Roman king of the gods (in Greek, Zeus). More than twice as massive as all the other planets put together, Jupiter could be regarded as a failed star; its composition of hydrogen and helium is similar to that of the Sun but it is not large enough for nuclear reactions to begin. Its zones and belts of clouds are driven by winds of up to 400 miles per hour. The Great Red Spot, a huge hurricane twice the size of the Earth, has been visible for over 300 years. Jupiter has 16 known moons, 4 of which were discovered by Galileo in 1610, including Ganymede, the largest moon in the Solar System. The two most recent were discovered in 1979.

For information about the real Jupiter go to Bill Arnott’s nine planet site: http://nineplanets.org/jupiter.html