Jupiter is the largest planet of the Solar System. If Earth were placed on the face of Jupiter, it would look like a 50 paise coin on a dinner plate. It weighs more than twice as much as all the other eight planets put together. It has sixteen known satellites. Jupiter is not only the biggest planet bur also the liveliest. It is full of mysteries and surprises. Its highest clouds are mainly crystals of frozen ammonia gas at a temperature of about -1400c. It is veiled in a turbulent, gaseous atmosphere made up of hydrogen and helium with significant amounts of ammonia and methane. The atmosphere. reaches thousands of kilometers deep to the surface. It gradually thickens into a churning liquid due to the immense pressures scientists assume that it finally turns into a liquid metallic core. At its centre, Jupiter has a small rocky core where temperatures probably reach 20,0000C, about three times the temperature of the Sun's surface. There may also be iron, silicon and other heavy elements in the rocky core. Jupittr seems to be more like the Sun in its composition than the other planets.
dropped through it. Sometimes it becomes pale plnk in colour and at other times a fiery orange red. For long, the Great Red Spot puzzled the astronomers. The Pioneer and Voyager missions to Jupiter revealed that the Red Spot is a huge cyclonic disturbance in the atmosphere. Jupiter is mainly a quick-spinning ball of gas and liquid with no solid surface. It also emits radio waves. Its composition, size and the number of moons gave rise to the idea that Jupiter is not a planet but rather a star with a "sdar system" of its own, that did1 not start 'burning'. It is estimated that if Jupiter,were just ten times heavier, it could have started to produce its own energy like the Sun. Jupiter's four largest satellites, 10, Europa, Ganymede and Callisto are called the Galilean satellites after Galileo, their discoverer. They are fascinating worlds in themselves. Io,,of diamw 3240 km, is almost like a fireball'with frequent-volcanic eruptions. Beyond 10 are Europa, diameter 3120 Km, Ganymede, diameter 4900 km and Callisto, diameter 4U0 lan. Europa is thought to'& made-up of frozen ice. - Ganymede and Callisto have a thick icy covering on them. The remaining satellites of Jupiter have not been so well studied.