Giovanni Cassini

Giovanni Domenico Cassini (June 8, 1625 - September 14, 1712) was an Italian astronomer and engineer. Cassini was born in Perinaldo, Genoa.

Astronomy

Cassini was an astronomer at the Panzano Observatory, from 1648 to 1669. He was a professor, of astronomy, at the University of Bologna and became, in 1671, director of the Paris Observatory.

Along with Hooke, Cassini is given credit for the discovery of the Great Red Spot (~1665). Cassini was the first to observe four of Saturn's moonss; he also discovered the Cassini Division (1675). Around 1690, Cassini was the first to observe differential rotation within Jupiter's atmosphere.

In 1672 he sent his colleague Jean Richer to Cayenne, French Guiana, while he himself stayed in Paris. The two made simultaneous observations of Mars and thus found its parallax to determine its distance, thus measuring for the first time the true dimensions of the solar system.

Cassini was the first to make successful measurements of longitude by the method suggested by Galileo, using eclipses of the satellites of Jupiter as a clock.

Engineering

Cassini was employed by the Pope in regard to fortifications, river management, and flooding of the Po.

Named after Cassini

• Cassini-Huygens Mission to Saturn
• The Cassini Division in Saturn's rings
• Cassini Regio, dark area on Iapetus
• Cassini crater, Mars