National Geographic : 1970 Aug
COURTESYMRS. SIMONEGOSSNERFROMGALILEO'S "IL SAGGIATORE," 1656 Galileo's own sketches, bearing the planetary signs (page 158), illustrate his epochal discoveries: the phases of Venus (next to a sun symbol at lower right), the rings of Saturn, and the blank disks of Jupiter and Mars, which man had seen earlier only as points of light. First to explore the planets by tele scope, Galileo Galilei (below) beheld awe some vistas. He launched the era of mod ern astronomy 360 years ago. Gazing at Venus, the Italian mathe matician detected its moonlike phases. This told him it revolves around the sun instead of Earth, supporting the then heretical theory of the Polish astronomer Copernicus of a sun-centered solar system. He delightedly observed four "little stars" attending Jupiter-the Galilean satellites-and puzzled over the strange configuration of Saturn. Training on the fiery solar disk itself, he saw sunspots and discovered that they moved about. FLORENCE;PHOTOGRAPH FROMSCALA Crude challengers of the infinite, two of Galileo's telescopes, each about 30 power, still point skyward. Ivory mount below them holds one of his cracked lenses. Al though a Dutch lens maker had invented the telescope a year earlier, in 1608, Gali leo was the first to train it on the heavens, using instruments he himself made. Treasures of the Institute and Museum of the History of Science in Florence, Italy, Galileo's telescopes escaped the 1966 Florence flood only when the director risked her life to snatch them from the torrent (GEOGRAPHIC, July 1967).