Galileo’s Telescopic Observations of the MoonAmong the many mechanical devices Galileo invented was a telescope that could magnify objects twenty times (other contemporary telescopes could magnify objects only three times). Using this telescope, he obtained the empirical evidence that proved the Copernican system. He sketched many illustrations of his observations, including the six phases of the moon, two of which are shown here. (moon: Biblioteca Nazionale, Florence, Italy/Rabatti- g- g-