Galileo Galilei: observation of Jupiter’s Medici satellites. He initially called them the Stars of Cosimo, but the name was later extended to include the four Medici brothers, one for each satellite: Cosimo, Francesco, Carlo, and Lorenzo. Simon Marius would coin the names Io, Europa, Ganymede, and Callisto, after names associated with Jupiter in Greek mythology. Galileo would grumble a bit and settle on neutral names: I, II, III, and IV. The Jupiter system would be visited by several automatic probes, several centuries after Galileo, and one of them would be named after the great scientist.
