Space probe

The first Cassini to explore Saturn was a person

Saturn
TWO CASSINIS The Cassini spacecraft has become famous for its stunning views of Saturn, including this image of the unlit side of the rings taken in 2012. But what do we know about the man Cassini was named for?

As the Cassini spacecraft plunges toward its death on Saturn, the world’s knowledge of the famous ringed planet continues to accumulate. Thanks to years of observations by the versatile probe, astronomers now know Saturn as intimately as macaroni knows cheese. But still hardly anyone outside the world of astronomy knows anything about Cassini — and I don’t mean the spacecraft, but the guy it was named for.

Gian Domenico Cassini was an Italian astronomer, born in Perinaldo in 1625, around the time that Galileo was battling the church over Copernicus’ revelation that the Earth orbits the sun. Cassini was attracted to poetry but was also good at math. He got his start in science via astrology, which back then was not considered quite as completely idiotic as it is today. In fact, astronomy itself was often supported by wealthy people in order to get better astrological forecasts. One such wealthy Italian, an amateur astronomer, was impressed with a pamphlet on astrology that Cassini had written; it earned him an invitation to work at the amateur’s observatory, near Bologna.

From the leading scientists at Bologna, Cassini learned the importance of using high-quality instruments to make the most precise measurements possible. His talents were soon recognized; by 1650 Cassini’s accomplishments and reputation earned him the chair in astronomy at the university in Bologna. He continued his research during the 1650s, taking a particular interest in comets.

Gian Domenico Cassini was an Italian astronomer who studied comets, the sun and solar eclipses. After mastering the moons of Jupiter, he turned to Saturn.

Cassini was an old-school conservative kind of scientist, not even inclined to take Galileo’s side on the Earth-orbiting-the-sun issue. Cassini preferred Tycho Brahe’s position that the other planets orbited the sun, but the sun then orbited the Earth. (Later Cassini accepted the Copernican sun-centered solar system, but only half-heartedly.) Cassini also was no fan of Newton’s law of gravity.

Cassini’s work as an eminent Italian scientist was not limited to astronomy. Called on to referee a…