Giovanni Cassini
DOI: 10.1063/PT.5.030981
It’s the birthday of Giovanni Cassini, who was born in 1625 in Perinaldo, Italy. In his first job, Cassini served as an assistant to the Marquess of Bismantova, who was a patron of astronomy and an amateur astronomer. By the age of 25, Cassini had learned enough astronomy to be appointed professor at the University of Bologna. In 1669 he was recruited to set up and run the Paris Observatory. There, he did his most important work. He determined the rotation periods of Mars and Jupiter, discovered four of Saturn’s moons (Iapetus, Rhea, Tethys and Dione) and observed differential rotation in Jupiter’s atmosphere. Cassini was also a surveyor. His method of determining longitude was used to measure the area of France accurately for the first time.
Date in History: 8 June 1625
