Who is jean dominique cassini

The construction of the Paris Observatory had just begun and Cassini was offered a generous salary, free accommodation, and a good travel allowance to oversee the project. The senate of Bologna and Pope Clement IX agreed to the trip which they believed would be a short one of at most two years.

After he became head of the Paris Observatory in , he soon changed his views on returning to Italy and became a French citizen two years later, changing his name to Jean-Dominique Cassini. There were two sons from this marriage, the younger one Jacques Cassini being born in and eventually succeeding to his father's position as head of the Paris Observatory.

At the Paris Observatory Cassini continued to make revolutionary discoveries, as he had done in Italy, using a telescope he had brought with him. He was the first to observe four of Saturn's moons: Iapetus , Rhea , Tethys , and Dione He discovered the gap in the ring system of Saturn now known as the Cassini division in Impressively he correctly proposed that the rings were composed of large numbers of tiny satellites each orbiting the planet.

This remained the best that was available prior to the invention of photography for astronomical purposes. Cassini's tables of Jupiter's moons were used to determine longitudes by providing a universal time with which to compare the local time at various positions on the Earth. While French expeditions measured the longitudes of numerous places, Cassini remained in Paris coordinating their data and making his own measurements.

From their data the first accurate value of the solar parallax was found, giving the distance from the Earth to the sun. Another measurement made by Jean Richer , namely that a pendulum with a period of one second is shorter in Cayenne than Paris, led him to explain this by suggesting that the Earth was flattened at the poles.

This supported theoretical proposals by Newton and Huygens , but Cassini did not accept Jean Richer 's explanation. He sought another experiment to determine whether the Earth was a perfect sphere. In order to determine the shape of the Earth, Cassini proposed measuring an arc of the meridian from the north of France to the south.

The project was begun in with Cassini making measurements from Paris towards the south, while Philippe de La Hire began making measurements north from Paris. The project was cancelled for financial reasons in when Cassini had reached Bourges, which is almost exactly in the centre of France.

In Cassini travelled in Italy. He took his eighteen year old son Jacques Cassini with him and they made numerous geodesic observations, as well as returning to Bologna where they repaired the gnomon at the Church of San Petronio in Bologna which Cassini had designed nearly thirty years before. In the meridian project was revived and now, in addition to a number of other scientists, Cassini had his son Jacques to assist him.

They made measurements of the meridian from Paris to Perpignan, which is 13 km west of the Mediterranean coast. During the Scientific Revolution , which took place between the 15th and 18th centuries, numerous inventions and discoveries were made that forever changed the way humanity viewed the Universe. And while this explosion in learning owed its existence to countless individuals, a few stand out as being especially worthy of praise and remembrance. An Italian astronomer, engineer, and astrologer, Cassini made many valuable contributions to modern science.

Educating by Jesuit scientists, he showed an aptitude for mathematics and astronomy from an early age. In , he accepted a position at the observatory at Panzano, near Bologna, where he was employed by a rich amateur astronomer named Marquis Cornelio Malvasia. During his time at the Panzano Observatory, Cassini was able to complete his education and went on to become the principal chair of astronomy at the University of Bologna by While there, he made several scientific contributions that would have a lasting mark.

This included the calculation of an important meridian line, which runs along the left aisle of the San Petronio Basilica in Bologna.

At This meridian also helped to settle the debate about whether or not the Universe was geocentric or heliocentric. He also studied the effects of refraction and the Solar parallax, worked on planetary theory, and observed the comets of and In recognition of his engineering skills, Pope Clement IX employed Cassini with regard to fortifications, river management and flooding along the Po River in northern Italy.

In , Cassini was named superintendent of fortifications and oversaw the fortifying of Urbino. While having bigger and more powerful telescopes, Cassini utilised buildings to house them in, one being the San Petronio Cathedral. The instrument was the so called Meridiana which could compute the exact date for Easter.

In after observations of Mars, he found the value of 24 hours 40 minutes for Mars's rotational period. We now know it to be 24 hours 37 minutes Cassini had formulated the hypothesis of infinite light but later on in his life dismissed this theory. In Cassini held the directorship to the Observatiore de Paris and two years later became a French citizen. 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.

Carried out primarily by the Jesuit Jean Picard , and later by Philippe de La Hire , this program included sunspot observations as well as measurements of the solar diameter. Cassini's own interests remained in geodesy and planetary astronomy. In he also discovered the main division of Saturn's ring, and correctly speculated on their physical constitution as being a collection of small debris.