Jupiter

Jupiter is the first and the largest of the jovian planets. It is composed mainly of turbulent gases. Its atmosphere, like the Sun has differential rotation. It rotates fastest at the equator and slowest at the poles. Perhaps the most distinctive feature of Jupiter is its Red Spot. This spot is stable in comparison with the rest of the atmosphere, which changes in structure over time. The Red Spot was first reported in 1664 and has been repeatedly observed since the nineteenth century. The Red Spot is an atmospheric eddy that is bigger than Earth. It is about 20,000 km by 50,000 km. The rest of the atmosphere is made up of alternating light and dark regions called zones and belts. The zones and belts have different temperatures.

Jupiter radiates more energy than it receives from the Sun. The interior of Jupiter is very hot; the internal heat is probably left over from the time of Jupiter's formation. Jupiter has a rocky core, a layer of metallic hydrogen and a molecular hydrogen layer. The metallic hydrogen is also called liquid hydrogen. This results from increasing density, pressure and temperature when moving toward the interior. The hydrogen becomes compressed so that the electrons and protons separate. The electrons and protons move around freely and can conduct electricity. Jupiter has a strong magnetic field due to the metallic hydrogen.

The discovery of four moons on Jupiter by Galileo was important because this was the first time that objects were found that were proven not to orbit around the earth. This observation gave support to the Copernican theory of the motions of the planets. These moons, Io, Europa, Ganymede, and Callisto, are known as Galilean moons.

moons: 16; the four large Galilean moons, Io, Europa, Ganymede and Callisto, and 12 smaller moons