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

Age	4.5 billion years, about the same age as Jupiter
Location	Solar system, in orbit around Jupiter
Avg. distance from Jupiter	1,882,700 km (1,170,000 mi)
Diameter	4,820 km (3,000 mi)
Mass	1.076 x 10²³ kg
Orbital period around Jupiter	16.7 days. The same side of Callisto 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	Callisto, the outermost of the four Galilean moons, has an old surface that is perhaps the most heavily cratered of any object in the solar system. The moon’s composition is roughly equal parts rocky material and water ice. Two enormous multi-ring impact structures are prominent features. Valhalla, the largest, has a central basin that is 600 km (370 mi) across and rings that extend to 3,000 kilometers (1,900 mi) in diameter. Asgard measures about 1,600 kilometers (1,000 mi) in diameter.