Giovanni Domenico Cassini

Giovanni Domenico Cassini, who also used the names Gian Domenico Cassini and, after settling in France, Jean-Dominique Cassini, was born in 1625 at Perinaldo in the Republic of Genoa and became one of the leading observers and applied mathematicians of the seventeenth century. He held the chair of mathematics and astronomy at the University of Bologna from 1650, designed a large meridian line in the church of San Petronio, and advised the Papal court on rivers and fortifications. Invited to Paris by Louis XIV in 1668, he headed the Paris Observatory from 1671 and became a French citizen. His observations of Jupiter, Mars and Saturn, including the gap in Saturn's rings that now bears his name, made his reputation. In mathematics he is remembered for the Cassinian curve, the locus of a point the product of whose distances from two fixed foci is constant, and for the identity for Fibonacci numbers that carries his name. He died in Paris in 1712.