Giovanni Domenico CassiniBorn 8 Jun 1625; died 14 Sep 1712 at age 87.Italian-French astronomer who discovered (1675) the dark gap subdividing Saturn's rings into two parts, now known as Cassini's Division. He stated that Saturn's ring, believed by Huygens to be a single body, was actually composed of small particles. Cassini also discovered four of Saturn's moons: Iapetus (Sep 1671), Rhea (1672) and on 21 Mar 1684, Tethys and Dione. He compiled new tables (1662) on the annual motion of the Sun. He observed shadows of four Galilean satellites on Jupiter (1664), and measured its rotation period by studying the bands and spots on its surface. He determined the period of rotation of Mars (1666), and attempted the same for Venus. His son Jacques was also an astronomer.«[A.k.a. Gian Domenico Cassini.] |
