11 Jupiter's Moons
Jupiter has 68 known moons. Its four largest moons are named the Galilean moons, after Galileo Galilei. Galileo first observed these moons in 1610. Io, Europa, Ganymede, and Callisto are very different worlds.
Io, Europa, Ganymede and Callisto are the mythological lovers of Zeus, the Greek counterpart to the Roman god, Jupiter.
The innermost Galilean moon, Io is the most geologically active object in our solar system with more than 400 volcanoes.
Slightly smaller than Earth's moon, Europa is thought to have a salty ocean just underneath its frozen surface. Last year, NASA's Hubble space telescope captured images of giant plumes of water vapor erupting from this moon's surface.
Ganymede is the largest moon in our solar system. With a diameter of 3,273 miles (5,268 km), it is larger than Mercury. Like Europa, Ganymede is believed to contain a salty ocean between two layers of solid ice.
The outermost Galilean moon, Callisto has a dark, cratered surface. It is slightly smaller than the planet Mercury.
Exploring the planets, moons and other bodies orbiting our sun.