Amazing Space- Fast Facts: Jupiter's moon, Ganymede

Age	4.5 billion years, about the same age as Jupiter
Location	Solar system, in orbit around Jupiter
Avg. distance from Jupiter	1,070,400 km (665,000 mi)
Diameter	5,268 km (3270 mi)
Mass	1.4819 x 10²³ kg
Orbital period around Jupiter	7.15 days. The same side of Ganymede always faces Jupiter. It takes the same amount of time to make one revolution on its axis as it does to complete an orbit around Jupiter.
Distinguishing features	Ganymede, one of the moons discovered by Galileo, is the largest moon in the solar system. It is even larger than the planet Mercury. Ganymede is the only moon in the solar system known to have a magnetic field. It has a spherical shape and is composed primarily of iron, rocks, and water ice, Below its icy surface is believed to be a salt-water ocean.