The biggest planet, Jupiter, is 11 times wider than Earth. It is made mainly of hydrogen and helium. Its rapid spin makes the clouds in its atmosphere form bands, called belts and zones.
Table 7. JUPITER DATA
|Diameter (width) at equator||88,849 miles (142,984 km)|
|Average distance from Sun||483.7 million miles (778.4 million km)|
|Time to orbit the Sun||11.87 years|
|Time to spin around own axis||9.93 hours|
|Mass||318 x Earth’s mass|
|Gravity||2.36 x Earth’s gravity|
|Cloudtop temperature||–166°F (–110°C)|
|Number of moons||61|
Jupiter’s four largest moons were discovered by Italian astronomer Galileo Galilei in 1610. Ganymede is the largest moon in the Solar System—it is 3,273 miles (5,268 km) across. Callisto is the most heavily cratered object in the Solar System, and Io is the most volcanic. Europa is covered with a blanket of water ice that may support primitive life.