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

Age	4.5 billion years, about the same age as Jupiter
Location	Solar system, in orbit around Jupiter
Avg. distance from Jupiter	421,700 km (262,000 mi)
Diameter	3,642 km (2,263 mi)
Mass	8.9319 x 10²² kg
Orbital period around Jupiter	1.77 days. The same side of Io 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	Io, the innermost of the four Galilean moons, is the most geologically active object in the solar system. With more than 400 volcanoes, Io’s mottled surface is constantly changing, painted in shades of red, yellow, white, black, and green. Unlike most solar system moons, which are composed of water ice, Io is mostly rock with an iron core.