<P> There are 69 known moons of Jupiter . This gives Jupiter the largest number of moons with reasonably stable orbits of any planet in the Solar System . The most massive of the moons are the four Galilean moons, which were independently discovered in 1610 by Galileo Galilei and Simon Marius and were the first objects found to orbit a body that was neither Earth nor the Sun . From the end of the 19th century, dozens of much smaller Jovian moons have been discovered and have received the names of lovers or daughters of the Roman god Jupiter or his Greek equivalent Zeus . The Galilean moons are by far the largest and most massive objects to orbit Jupiter, with the remaining 65 known moons and the rings together comprising just 0.003% of the total orbiting mass . </P> <P> Of Jupiter's moons, eight are regular satellites with prograde and nearly circular orbits that are not greatly inclined with respect to Jupiter's equatorial plane . The Galilean satellites are nearly spherical in shape due to their planetary mass, and so would be considered (dwarf) planets if they were in direct orbit around the Sun . The other four regular satellites are much smaller and closer to Jupiter; these serve as sources of the dust that makes up Jupiter's rings . The remainder of Jupiter's moons are irregular satellites whose prograde and retrograde orbits are much farther from Jupiter and have high inclinations and eccentricities . These moons were probably captured by Jupiter from solar orbits . Eighteen of the irregular satellites have not yet been named, and nine of them do not have their orbits known well enough to be numbered . </P>

How many moons are there in the jupiter