However he also used the name Gian Domenico Cassini, and after he moved to France, he changed his name to the French version of Jean-Dominique Cassini. To add just one more comment to the question of his name, he was the first of the famous Cassini family of astronomers and as such is often known as Cassini I. We know little of his parents but certainly his father was a Tuscan. In fact Giovanni was brought up, not by his parents but by an uncle, a brother of his mother Julia Crovesi.
After spending two years being educated at Vallebone, Cassini entered the Jesuit College at Genoa where he studied under Casselli. After this he studied at the abbey of San Fructuoso. Taton writes [ 1 ] :- He showed great intellectual curiosity and was especially interested in poetry, mathematics and astronomy.
His first interest, however, was in astrology rather than astronomy. He read widely on this topic and soon was very knowledgeable, yet was convinced that there was no truth in astrological predictions. It was, rather strangely, his extensive knowledge of astrology that led to his first appointment. In the Marquis Cornelio Malvasia, who was a senator from Bologna with a great interest in astrology, invited Cassini to Bologna. He offered him a position in the Panzano Observatory which he was constructing at that time.
From Cassini observed at the Panzano Observatory with instruments which he had purchased with financial resources from the Marquis Malvasia. This was an important time for Cassini who learnt much from the outstanding Jesuit scientists Giovanni Battista Riccioli and Francesco Maria Grimaldi who later discovered diffraction. In , Cassini became professor of mathematics and astronomy at the University of Bologna, filling the chair which had been vacant since the death of Cavalieri at the end of November This appointment came about through the support of the Marquis Malvasia whose important position in Bologna gave him considerable influence in naming Cavalieri 's successor.
Cassini observed a comet in - 3 and he published an account of his observations which he dedicated to the Duke of Modena. From the work we can see that at this time Cassini believed in an Earth centred solar system, with comets beyond Saturn but originating from the Earth. Observations would lead him to accept the model of the solar system proposed by Tycho Brahe and, in , he presented an Earth centred system with the moon and sun orbiting the Earth and the other planets orbiting the sun.
Later he came to accept a version of the Copernican model. One of Cassini's predecessor's as professor of mathematics and astronomy at Bologna had been Egnatio Danti who had been appointed in Danti had built a gnomon at the Church of San Petronio in Bologna, one of the largest Christian churches ever built. He also served as a professor of astronomy at the University of Bologna. However, his work as the director of the Paris Observatory had arguably the greatest impact on the scientific world.
He enthusiastically adopted his new country, adapting his name to the French language and becoming a citizen in Astronomy wasn't the only science Cassini was involved in. According to a biography of Cassini by the University of St. Andrews, "He was an expert in hydraulics and engineering and as such was consulted regarding the dispute of between Bologna and Ferrara on the course of the River Reno.
The dispute was settled by Pope Alexander VII with advice from Cassini and for several years after this he was regularly consulted by the Papal Court as an expert on river management. In , Cassini's colleague Jean Richer went to Cayenne, French Guiana, while Cassini stayed in Paris so that the two could make simultaneous observations of Mars and, by computing the parallax , determined its distance from Earth.
This allowed for the first estimation of the dimensions of the solar system. He died in Parison 14 September Cassini established his reputation in Italy by careful and accurate solar and planetary measurements, which allowed him to produce improved planetary tables, as well as improved versions of " Galileo's tables " for the " moons of Jupiter " , then of great interest because of their potential use for determining longitudes at sea.
He was also involved in numerous engineering projects, including fortifications and hydraulics. While in Bologna Cassini also measured the rotation periods of Mars and Jupiter. As director of the Observatoire de Paris, Cassini inaugurated, among other projects, a sustained solar observing program.
These laws state that:. Thanks to his leadership, Giovanni Cassini was the first of four successive Paris Observatory directors that bore his name. Cassini named these moons Sidera Lodoicea the stars of Louis , and correctly explained the anomalous variations in brightness to the presence of dark material on one hemisphere now called Cassini Regio in his honor. He also theorized that the rings were composed of countless small particles, which was proven to be correct.
After dedicating his life to astronomy and the Paris Observatory, Cassini went blind in and then died on September 14th, , in Paris. And although he resisted many new theories and ideas that were proposed during his lifetime, his discoveries and contributions place him among the most important astronomers of the 17th and 18th centuries. As a traditionalist, Cassini initially held the Earth to be the center of the Solar System.
In time, he would come to accept the Solar Theory of Nicolaus Copernicus within limits, to the point that he accepted the model proposed by Tycho Brahe. However, he rejected the theory of Johannes Kepler that planets travel in ellipses and proposed hat their paths were certain curved ovals i. Cassinians, or Ovals of Cassini.
For his lifetime of work, Cassini has been honored in many ways by the astronomical community. Because of his observations of the Moon and Mars, features on their respective surfaces were named after him.
Then there is Asteroid Cassini, which was discovered by C.
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