Jupiter has sixty-seven moons.
More Info: Jupiter has many moons and satellites most of which are less than ten kilometers in size. Of the sixty-seven known moons of Jupiter (as of 2012), only seventeen are larger than 6.2 miles in diameter. [“Jupiter’s Moons: Facts About the Largest Jovian Moons” Space.com]
Galilean Moons of Jupiter
Floating around Jupiter are four of the largest moons in the entire Solar System. These four moons were discovered by Galileo Galilei in the seventeenth century, and as such are named the Galilean Moons. These moons are Io, Europa, Callisto, and the largest moon of all, Ganymede. [“Solar System Exploration: Planets: Jupiter: Moons.” NASA]
Of all the moon’s orbiting planets in the solar system, Ganymede is the largest, almost half as big as Earth and larger than the planet Mercury. It orbits the planet Jupiter roughly every seven days. Various space probes have studied Ganymede and discovered that is has a thin oxygen atmosphere and presumably an underground ocean two hundred kilometers beneath the ice surface. [“Ganymede (moon).” Princeton University]
The Nature of the Moons that Orbit Jupiter
Eight of the moons of Jupiter are considered to have regular, that is circular, orbits. The rest of the moons have irregular orbits and are generally much further away from the planet itself. These moons have eccentric orbital patterns and were likely satellites that were captured from solar orbits. [“The Moons of Jupiter” School of Astronomy and Space Science]
“Jupiter’s Moons: Facts About the Largest Jovian Moons | Space.com .” Space and NASA News – Universe and Deep Space Information | Space.com . N.p., n.d. Web. 6 Jan. 2013. <http://www.space.com/16452-jupiters-moons.html>.
“Solar System Exploration: Planets: Jupiter: Moons.” NASA Solar System Exploration. N.p., n.d. Web. 6 Jan. 2013. <http://solarsystem.nasa.gov/planets/profile.cfm?Display=Moons&Object=Jupiter>.
“Ganymede (moon).” Princeton University. N.p., n.d. Web. 6 Jan. 2013. <http://www.princeton.edu/~achaney/tmve/wiki100k/docs/Ganymede_(moon).html>.
“The Moons of Jupiter: Chapter 11, Section 5.” School of Astronomy and Space Science. N.p., n.d. Web. 6 Jan. 2013. http://astronomy.nju.edu.cn/~lixd/GA/AT4/AT411/HTML/AT41105.htm