Moons of Jupiter around Ganymede. In 2016, the "Juno" spacecraft imaged the Galilean moons from above their orbital plane as it approached Jupiter orbit insertion, creating a time-lapse movie of their motion. Moons of Jupiter There are 79 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
Ganymede (moon) seven days and three hours. Like most known moons, Ganymede is tidally locked, with one side always facing toward the planet, hence its day is seven days and three hours. Its orbit is very slightly eccentric and inclined to the Jovian equator, with the eccentricity and inclination changing quasi-periodically due to solar and planetary gravitational perturbations on a timescale of centuries. The ranges of change are 0.0009–0.0022 and 0.05–0.32°, respectively. These orbital variations cause the axial tilt (the angle between rotational and orbital axes) to vary between 0 and 0.33°. Ganymede participates in orbital resonances with Europa and Io: for