Jupiter+the+3

Unlike Saturn's intricate and complex ring patterns, Jupiter has a simple ring system that is composed of an inner halo, a main ring and a Gossamer ring. To the Voyager spacecraft, the Gossamer ring appeared to be a single ring, but Galileo imagery provided the unexpected discovery that Gossamer is really two rings. One ring is embedded within the other. The rings are very tenuous and are composed of dust particles kicked up as interplanetary meteoroids smash into Jupiter's four small inner moons [|Metis], [|Adrastea], [|Thebe], and [|Amalthea]. Many of the particles are microscopic in size. The innermost halo ring is toroidal in shape and extends radially from about 92,000 kilometers (57,000 miles) to about 122,500 kilometers (76,000 miles) from Jupiter's center. It is formed as fine particles of dust from the main ring's inner boundary 'bloom' outward as they fall toward the planet. The main and brightest ring extends from the halo boundary out to about 128,940 kilometers (80,000 miles) or just inside the orbit of Adrastea. Close to the orbit of Metis, the main ring's brightness decreases. The two faint Gossamer rings are fairly uniform in nature. The innermost Amalthea Gossamer ring extends from the orbit of Adrastea out to the orbit of Amalthea at 181,000 kilometers (112,000 miles) from Jupiter's center. The fainter Thebe Gossamer ring extends from Amalthea's orbit out to about Thebe's orbit at 221,000 kilometers (136,000 miles). Jupiter's rings and moons exist within an intense radiation belt of electrons and ions trapped in the planet's magnetic field. These particles and fields comprise the jovian [|magnetosphere] or magnetic environment, which extends 3 to 7 million kilometers (1.9 to 4.3 million miles) toward the Sun, and stretches in a windsock shape at least as far as Saturn's orbit - a distance of 750 million kilometers (466 million miles). 

Named after Jove, the chief god of Roman mythology, Jupiter is the fifth planet from the Sun and the largest planet in Earth's solar system. Besides the Sun, the Moon, and Venus, Jupiter is the brightest object in Earth's sky, often mistaken as a star. Jupiter is more than three times brighter than Sirius, the brightest star.The Italian scientist, [|Galileo Galilei] was the first astronomer to view Jupiter through a telescope. While viewing Jupiter, he observed four satellites orbiting the planet, which lent credence to the Copernican theory that the Earth and other planets revolve around the Sun. Previously, many people held to the belief, developed by 2nd century astronomer, Ptolemy, that everything revolved around the Earth. Galileo's discovery was a major step forward for astronomy.Jupiter's satellites are mostly named for his mythological lovers. Many smaller moons have been discovered recently, but are as yet unnamed.
 * MEAN RADIUS: 69911 km
 * MASS: 317.8 (Earth=1)
 * DENSITY: 1.31 (g/cm^3)
 * GRAVITY: 2.34 (Earth=1)
 * ORBIT PERIOD: 11.86 (Earth years)
 * ROTATION PERIOD: .414 (Earth days)
 * SEMIMAJOR AXIS OF ORBIT: 5.2 au
 * ECCENTRICITY OF ORBIT: 0.004