Cassini: the 17th-century astronomer who shrank France and inspired a spacecraft | Rebekah Higgitt

The Cassini spacecraft and its dramatic dive towards Saturn have been in the news this week, but the human Cassini is no less memorable

As a historian of science, when I scroll through my Twitter timeline and see mentions of Cassini, my thoughts tend to go not to the spacecraft that is, at the time of writing, somewhere between Saturn's rings and the planet itself. Rather, they turn to Cassini I, II, III and IV, the 17th and 18th-century dynasty of Paris Observatory directors. With the word Saturn appearing alongside, I fix on Cassini I, Giovanni Domenico (or, after he moved to France, Jean-Dominique) Cassini.

Giovanni Domenico Cassini was the first director of the observatory founded by Louis XIV and, among much else, he discovered two of Saturn's moons, the planet's equatorial belt and a division in its rings. This last has been named the Cassini Division in his honour. Thus the Cassini Spacecraft has imaged the Cassini Division that was first depicted by Cassini I. It can just be seen in the image at the top, which was published in 1676 in the Philosophical Transactions of the Royal Society.