1610

Galileo builds a 30X telescope. He uses the telescope to make several important astronomical discoveries, including four moons of Jupiter, the ring of Saturn, the phases of Venus, and craters and mountains of the moon. His observations of moons revolving around Jupiter confirm for him the correctness of the Copernican model. Galileo also concludes from the irregular features of the moon that the moon is composed of matter similar to that of earth.