The Galilean Moons are the four largest moons of Jupiter. They are much different from the other 77 moons, in terms of appearance, composition, and size. They were named so because they were discovered by Italian astronomer Galileo Galilei, but also discovered and named by German astronomer Simon Marius, using names suggested by Johannes Kepler's Mundus Jovialis, published in 1614. However, early astronomer Xi Zezong claimed that a "small reddish star" observed close to Jupiter in 362 BC by early astronomer Gan De may have been Ganymede, predating Galileo's discovery by around almost 2000 years.
- Pasachoff, Jay M. (2015). "Simon Marius's Mundus Iovialis: 400th Anniversary in Galileo's Shadow". Journal for the History of Astronomy 46 (2): 218–234. Bibcode 2015AAS...22521505P. doi:10.1177/0021828615585493.
- Zezong, Xi, "The Discovery of Jupiter's Satellite Made by Gan De 2000 years Before Galileo", Chinese Physics 2 (3) (1982): 664–67.