Jupiter

Jupiter is the largest planet in the solar system with a diameter of 142,984 kilometers, it has 1330 times the volume and 318 times the mass of Earth. Jupiter is 816 million kilometers from the Sun and appears as the fourth largest object in the sky as viewed from Earth (Sun, Moon and Venus are brighter).

A Jovian year consists of 4333 Earth days, although a day only lasts 9.84 hours. This rapid rotation combined with Jupiter's very active atmospheric weather pattern gives Jupiter a very violent appearence. Pioneer 10, Voyager 1 and 2 all made close up fly-bys between March 1972 and July 1979. Jupiter does not have a solid surface or a molten core, but rather it is gaseous and has a small, solid core. Above the core is a sphere of frozen water combined with frozen ammonia that is 6880 kilometers thick, which is kept frozen by immense pressure rather than temperature. This enourmous block of ice averages 15,000 degrees C. Above this is a layer of liquid metallic hydrogen 46,000 kilometers deep, topped by a 16,000 kilometer ocean of liquid hydrogen. The temperature of the liquid hydrogen is 150 degrees C. Above this is the planets turbulent atmosphere. It's atmosphere contains acetylene, ethane, methane, ammonia, carbon monoxide, phosphine and even water.

The most outstanding feature on Jupiter is the Great Red Spot (GRS), First recorded in 1664 by Robert Hooke. It is three times the size of Earth, and is a giant cyclonic storm. It rotates anticlockwise, and makes a complete rotation every six Earth days.

In 1979, the Voyager spacecraft discovered a distinct ring system. The Jovian rings are very thin compared to Saturn's. The ring system is divided in two parts that begin 46,000 kilometers above Jupiter's cloud tops. The two parts are a faint band 5000 kilometers across, feathering into a brighter band 800 kilometers across. The rings are composed of dark grains of sands and dust, and are probably not more than 1.6 kilometers thick.