Events

In January of 1610, exactly 400 years ago, Galileo turned his newly constructed telescope toward the heavens and was the first to observe the 4 moons of Jupiter that are now known as the Galilean moons. This observation, along with his later studies of the motions of sunspots and the phases of Venus, spelled the death of the Ptolemaic view of an Earth-centered universe, which was replaced with the Copernican heliocentric model.