Quarter 1 Biography: Gian Cassini

Quarter One Biography: Gian Cassini

Gian Cassini was a fundamental astronomer of the sixteenth and seventeenth centuries. Born in France during June of 1625, Cassini was born into a family that was very interested in astronomy. He was raised by his mother’s brother and studied at a Jesuit College in Genoa in addition to an abbey located in San Fruttuoso. Cassini showed an interest in the heavens right away. Because of this Marquis Cornelio Malvasia, the senator of Bologna and an astronomer, invited Cassini to work with him in his observatory. For 21 years Cassini worked with the Marquis while still learning the tools of the trade. One of Cassini’s other tutors was Francesco Maria Grimaldi, the man responsible for discovering the phenomenon of diffraction. Although Gian had excellent teachers, many people say that these teachers taught Cassini the Geocentric view of the universe that Gian upheld throughout his lifetime. Cassini soon became fairly popular and was later given the Principle Chair of Astronomy at the university in Bologna. Three years later, Cassini proved himself again as an elite astronomer. He did this by successfully constructing an accurate meridian; a measuring device like a sundial, after the previous obsolete meridian was no longer usable. Once the meridian was built Cassini was able to take precise measurements of the exact positions of solstices and equinoxes.

During the next nine years, Cassini took a break from solely studying the heavens. Gian wrote several memoirs about the flooding of the Po River, and even instituted some experiments involving hydraulics. He was also appointed superintendent of the rivers when the cities of Bologna and Ferrara were in dispute over the path of the rivers. This basically meant that is was Cassini’s duty to defend the papal view of controlling and regulating the Chiana River.  He also participated in studying blood transfusions and insects. Even though Cassini diverged from astronomy, the passion for the skies came back. During the beginning of the 1660’s Cassini published observations of solar eclipses and comets. In addition to making publications with the naked eye, Cassini’s relations with the lens makers Giuseppe Campani and Eustachio Divini allowed him to obtain a telescope. Using this telescope, Gian was able to make very precise and accurate observations that soon added up to an extensive collection worthy of Tycho Brahe. Cassini was able to see Jupiter with its moons and estimate the approximate length of rotation for the satellites. Not only did Gian observe that Jupiter itself was flattening, but also that Jupiter had spots and bands. Cassini was able to complete the Jovian tables of movement that Galileo could not. In 1668, Jean Colbert, the finance minister of France, invited Gian Cassini to the newly established Académic Royale des Sciences Academy. Cassini would be the head of the Royal Observatory. By using telescopes that had focal lengths between 17-136 feet, Cassini was able to identify three more moons around Saturn and the dark circle in the rings of Saturn. This divide in the rings is now referred to as the Cassini Divide. Gian was also able to map out an extensive portion of the lunar surface. Later in 1672, Cassini and fellow astronomers were able to estimate the length of the astronomical unit, or the distance from the Earth to the Sun. Jean Richer and Gian Cassini were able to determine the distance by using measurements associated with Mars’ opposition. This was quite achievement because astronomers were now able to approximate the size of the universe. While in France, Gian met his wife during 1674, and had two boys. The youngest of the sons followed in the footsteps of his father and became an astronomer.

Throughout Gian Cassini’s life he renounced the heliocentric view of the universe and the laws of gravitation proposed by Sir Isaac Newton. Even though Cassini did not agree with these theories, he was able to accomplish many things in the field of astronomy. Toward the end of Cassini’s life, in 1710, he went completely blind. Cassini eventually died in 1712 at the age of 87. Cassini leaves a legacy and for that reason, NASA launched a satellite named after Cassini, whose mission is to investigate Saturn. A crater on The Moon and a crater on Mars are named in honor of Gian Cassini as well. All in all, Cassini made essential contributions during his lifetime that has a lasting effect.