Moons of Jupiter
Planet Jupiter is known to have 79 natural satellites or moons, and collectively they are referred as Jovian moons.
A special group under Jovian moon is called Galilean moons. Galilean moons were the moons which were discovered by astronomer Galileo Galilei in 1610. This special group include Europa, Io, Callisto and Ganymede.
Io is named after the Greek mythological character Io who was one of mortal lovers of Zeus, the Greek god of sky and counterpart of Roman Jupiter. Astronomer Simon Marius named this natural satellite of Jupiter as Io in 1614.
Europa, also known as Jupiter II, is the one of a Jovian moons category - Galilean Moons. It is the sixth closest natural satellite to the planet Jupiter. Europa has the smoothest surface of any known solid object in the solar system. Europa is also the sixth largest natural satellite in the solar system.
Ganymede, also known as Jupiter III, one of Jovian moon, is the largest and the massive natural satellite in the solar system. It is also the ninth largest object in the solar system, even larger than the planet Mercury. Ganymede is one of four Galilean Moons – a special group of moons under Jovian moons – which were discovered by Galileo Galilei. Ganymede is seventh in line from the Jupiter.
Callisto, also known as Jupiter IV, is the second-largest moon of the Jupiter. It is the third largest natural satellite in the solar system after Ganymede and Saturn’s Titan.
Callisto is the outermost of four Galilean moons of Jupiter. It orbits at a distance of 1,880,000 KM from the Jupiter.