Jupiter is the fifth planet from the Sun and is the largest one in the solar system. If Jupiter were hollow, more than one thousand Earths could fit inside. It also contains more matter than all of the other planets combined. Jupiter has 28 .
known satellites, four of which were observed by Galileo in 1610. These satellites are named Callisto, Europa, Ganymede and Io. There is a ring system and is totally invisible from the Earth. The rings were discovered in 1979 by Voyager 1. Jupiter's atmosphere is somewhat like the Sun. It is composed mainly of hydrogen and .
helium. Jupiter contains 90% hydrogen and 10% helium, with small amounts of methane, ammonia, water vapor and other compounds. Within Jupiter, the pressure is so enormous that the hydrogen atoms are broken up and the electrons are freed .
so that the remaining atoms are bare protons. This results in hydrogen becoming metallic.
Colorful bands, atmospheric clouds and storms describe Jupiter's weather systems. The cloud patterns change within hours or days. The Great Red Spot is a storm moving in a counter-clockwise direction. Smaller storms can be found through out the clouds of Jupiter. .
Jupiter has a simple ring system that is composed of an inner light, a main ring and a Gossamer ring. To the Voyager spacecraft, the Gossamer ring appeared to be a single ring, but Galileo's images provided the discovery that the Gossamer is really two rings. One ring is planted within the other. The rings are very weak and are composed of dust particles. Many of the particles are microscopic in size. .
The innermost ring extends from about 57,000 miles to about 76,000 miles from Jupiter's center. It is formed from particles of dust. The main and brightest ring extends to about 80,000 miles. Jupiter's four small inner moons are Metis, Adrastea, Thebe, and Amalthea. Close to the orbit of Metis, the main ring's brightness decreases. Jupiter's rings and moons exist within a strong radiation belt of electrons and ions trapped in the planet's magnetic field.