Jupiter's Moons

Jupiter's Moon montage
A montage of Jupiter's Moons
Credit: NASA/JPL

Jupiter has 79 confirmed moon's orbiting around it, which is the largest number of any planet in our Solar System. Twelve of these moons were only confirmed in 2018 by the NASA Juno Spacecraft. The four largest moons are known collectively as the Galilean Moon's as they were discovered by Galileo in the year 1610.

The rest of Jupiter's moons are much, much smaller. In fact if you added together the other 75 moons they would have a mass of only around 1/4500th of the smallest Galilean moon, Europa.

Jupiter also has a ring around it, but it is much less spectacular than the rings of Saturn, and very faint.

Facts and Figures Io Europa Ganymede Callisto
a 1 Earth Mass = 5,980,000,000,000,000,000,000,000 kg
Distance from Jupiter (km) 421,600 670,900 1,070,000 1,883,000
Radius (km) 1,815 1,569 2,631 2,400
Mass (Earth Masses) a 0.015 0.008 0.025 0.018
Time of Orbit (Earth Days) 1.77 3.55 7.15 16.69
Day Length (Earth Days) 1.77 3.55 7.15 16.69