On January 7, 1610, the Italian astronomer Galileo discovered three of Jupiter's moons: Callisto, Europa and Io. When he looked at Jupiter through his telescope, he saw what he thought were three tiny ...
Source: NOVA: "Galileo's Battle for the Heavens" This resource was adapted from NOVA: "Galileo's Battle for the Heavens." In 1610, when Galileo first pointed his newly built telescope toward the sky, ...