Jupiter is the largest planet in our solar system. It is 318 times the mass of the Earth, and is 11 time greater in diameter. Even though Jupiter is huge, it is still 1,000 times smaller than the Sun. Jupiter revolves around the Sun only once every 12 years at a distance of 465,000,000 miles. Jupiter is spinning at a very high rate of speed for such a large object, rotating once on its axis every 9 hours 55.5 minutes. This causes the shape of Jupiter to be oblate (flat on the top and bottom.) The speed of rotation is probably the cause for the colorful bands. The bands are shades of orange, brown, gray, yellow, cream, and light blue. Jupiter is a very turbulent planet with storms, clouds, and even lightening. The appearance of Jupiter changes within a few days due to the turbulence on the cloud surface.
The Great Red Spot in the clouds of Jupiter is a gaseous island or a giant storm many times the size the of the Earth. It is very similar to an anticyclone, meaning high pressure as opposed to a cyclone, which is low pressure. Jupiter's bands and belts are visible from Earth based telescopes. These bands are rotating at different speeds from each other and cause the vortices that become the visible storms.
The central core of Jupiter is composed of ultra compressed hydrogen gas surrounding a rocky central core that is 20 Earth masses of iron and silicates (sand). The next layer out is liquid metallic hydrogen, followed by liquid molecular hydrogen. The liquid metallic regions make up about 75% of Jupiter's mass.
Four of the at least 16 Galilean satellites, (Io, Europa, Ganymede, and Callisto,) that orbit Jupiter are easily visible in binoculars or a telescope.
Io has the only known active volcanoes other than Earth. The surface of Io is constantly changing due to volcanic activity. Volcanic plumes are visible in pictures of Io that were sent back by Voyager.
Europa's surface is shiny and thought be made up of ice. The surface has NO visible craters but has numerous dark lines criss-crossing almost the entire surface. These lines are possibly fracture lines from freezing water. It is also believed that the surface of Europa has no visible craters because it is fairly "fresh", or that it has a cycle of rejuvenation.
Ganymede is the largest satellite in the solar system. It is larger than Mercury and just a little smaller than Mars. Its surface is heavily cratered and it also has many channels. The channels may have been caused by the shifting of the frozen ice on the surface, sort of a glacier effect.
Callisto has a very dark surface that is peppered with numerous meteor / impact craters. There is large crater which forms a great basin, Valhalla, measuring 600 km (372 miles) in diameter.