Galileo Galilei made a significant contribution to science when he discovered four satellites of Jupiter. These moons were first observed as of January 1610, and were originally named the “Medicean planets.”
Each of the individual moons were numerically numbered as I, II, III and IV, this naming system was used for over two hundred years. As of the mid 1800s the Galilean moons adopted the names Callisto, Ganymede, Europa and Io. It became apparent that the number system would be confusing with the discovery of all the additional new moons.
As of January 2011, the planet Jupiter has 50 officially named satellites. There are 13 other moons proposed for the planet based on various observations; these discoveries have not yet been named nor confirmed. The 50 satellites on Jupiter include: Metis, Adrastea, Amalthea, Thebe, Io, Europa,
Ganymede, Callisto, Themisto, Leda, Himalia, Lysithea, Elara, Carpo, Euporie, Orthosie, Euanthe, Thyone, Mneme, Harpalyke, Hermippe, Praxidike, Thelxinoe, Iocaste, Ananke, Arche, Pasithee, Herse, Chaldene, Kale, Isonoe, Aitne, Erinome, Taygete, Carme, Kalyke, Eukelade, Kallichore, Helike, Eurydome, Autonoe, Sponde, Pasiphae, Megaclite, Sinope, Hegemone, Aoede, Callirrhoe, Cyllene, Kore.
After Galileo Galilei made this great contribution to science, Copernicus dismissed the earth-centric theory in favor of the helio-centric theory.