Astronomers discovered 17 moons around JUPITER. The four larger ones are called the Galilean Moons after the Italian Scientist Galiloe, who discovered them in 1610. These four Galilean moons, even without their resonance, are amongst the most fascinating celestial bodies. The others which are smaller moons may just be asteroids, captured by the planet’s gravity. The Galileo spacecraft was launched to investigate these moons, particularly Europa, in an effort to lay to rest some of these long standing questions.
Ganymede is the largest moon in the Solar System. It is even bigger than the planet Mercury.
Lo is covered with volcanoes that pours sulfur onto its surface.
Callistro is a ball of dusty ice. Its surface is scarred with hundreds of craters.
Europa may have a deep ocean beneath its fractured, icy crust. Some scientists believe that this ocean may contain living organisms.
There are great deal of tidal resonance among the moons. These resonances are caused by magnetism effects between Jupiter and the Galilean moons. The magnetic attraction helps to keep these moons in place while orbiting Jupiter.