Chinese astronomical records report that in 365 BC, Gan De detected what might have been a moon of Jupiter, probably Ganymede, with the naked eye. However, Gan De reported the color of the companion as … See more

Ganymede orbits Jupiter at a distance of 1,070,400 kilometres (665,100 mi), third among the Galilean satellites, and completes a revolution every seven days and three hours … See more

Size
With a diameter of about 5,270 kilometres (3,270 mi) and a mass of 1.48×10 tonnes (1.48×10 kg; … See more

Several spacecraft have performed close flybys of Ganymede: two Pioneer and two Voyager spacecraft made a single flyby each between 1973 and 1979; the Galileo spacecraft made six passes between 1996 and 2000; and the Juno spacecraft performed two … See more

Galileo claimed the right to name the moons he had discovered. He considered "Cosmian Stars" and settled on "Medicean Stars", in honor of Cosimo II de' Medici.
The French … See more

Ganymede probably formed by an accretion in Jupiter's subnebula, a disk of gas and dust surrounding Jupiter after its formation. The accretion of Ganymede probably took about … See more

• Voyager 1's image of Ganymede taken in March 1979 during its flyby of Jupiter.
• Voyager 2's image of Ganymede taken from a distance of … See more