Giovanni Cassini Biography

Giovanni Cassini also known as Giovanni Domenico, Gian Domenico Cassini, and Jean Domenico Cassini is a very famous astronomer who has made many discoveries and innovations that have greatly benefited the world of astronomy. He was born in Italy in 1625 in a Roman Catholic family, Cassini worked in the family business of astronomy by making maps including one of the first topographic maps of France using Frisius’s technique of triangulation. At a young age, he studied rotational periods of planets before moving to France upon invitation by King Louis XIV. In 1648, he began work in the Panzano Observatory with instruments he bought from the Marquis Malvasia. Using these, he observed a comet in 1652 and named it after the Duke of Modena. He actually used methods set up by Galileo to make the first accurate measurements of longitude and used that to measure the size of France. Cassini is the first person to observe four of Saturn’s moons, Iapetus in 1671, Rhea in 1672, Tethys in 1684 and Dione in 1684. He named them Louisian Stars after King Louis. Iapetus had variations in brightness, which he accurately ascribed to the presence of dark material on one hemisphere, which is now called Cassini regio in his honor. In 1672, Cassini collaborated with a man named Jean Richer who went to Cayenne so they could both make observations of Mars and to calculate the parallax to find the distance between Earth and Mars. This actually allowed for the first estimations of the dimensions of the solar system. He also discovered the Cassini Division in the rings of Saturn in 1675 as well as the Great Red Spot on Jupiter in 1665. In 1712, Giovanni Cassini died in Paris, France thus ending the list of a long series of discoveries and observations made by an amazing astronomer.