Jupiter and its moons form a planetary group of incredible beauty (Figure 9.1).The giant planet has a volume 1300 times greater than the Earth, but its near-surface layers are composed mostly of gases swirling in complex patterns.
As it is, Jupiter radiates more energy than it receives from the Sun.
The heat emitted from it may have been sufficient to drastically alter the composition of its satellites as they formed from the condensing solar nebula.
Jupiter and the rest of the giant planets are fundamentally different from the rocky inner planets.
Besides being larger, they are composed predominantly of gas and have no solid surfaces at all.
This moon did not expand during its late history and, because of its distance from Jupiter, it received little energy from tidal heating.7.
The satellites of Jupiter appear to have condensed and then accreted in a thermal gradient centered on Jupiter.
Therefore, the inner moons are refractory, silicate-rich, and ice-poor whereas the outer moons are ice-rich.
The characteristics of Jupiter, which orbits the Sun at a distance five times that of Earth, exemplify many features of the outer planets (those that lie beyond the orbit of Mars). It has a diameter of 143,800 km, more than ten times that of the Earth.
A vast amount of data has been returned to Earth by several flyby spacecraft, including Pioneers 10 and 11 (19), Voyagers 1 and 2 (1979), and Galileo (1995-2003).