Giovanni Domenico Cassini

Research by Josh Nappa

Personal Information

General facts about this person such as dates of birth and death, country of origin, education, family, where he or she worked or taught, etc.

  • Born June 8, 1625 in Perinaldo, Republic of Genova (Modern day Italy)
  • Son of Jacopo Cassini and Julia Crovesi
  • Accepted position at observatory at Panzano, near Bologna in 1648
  • After being educated there under the teachings of Giovanni Battista Riccioli and Francesco Maria Grimaldi for just two years, Cassini was appointed as the principal chair of astronomy at the University of Bologna.
  • Cassini moved to France in 1669 to help create the Paris Observatory with a grant from King Louis XIV.
  • Upon completion of the observatory, Cassini became the director of the facility until his death.
  • He also served as the astronomer/astrologer to Louis XIV.
  • A year after going blind in 1711, Cassini died on September 14, 1712 in Paris at the age of 87.

Major Contributions to Astronomy

  • First to observe four of Saturn's moons; Lapetus, Rhea, Tethys, and Dione.
  • He and a colleague, Jean Richer, made observations of Mars from two different locations at the same time which they used with the parallax effect to determine the distance of Mars to Earth.
  • Using methods made by Galileo, Cassini made the first measurements of longitude which he used to measure the size of France accurately for the first time.
  • He discovered the Cassini Division in the rings of Saturn
  • First to observe differential rotation in the atmosphere of Jupiter.

Cassini's Challenges

Cassini wasn't really opposed in his works, however he opposed Issac Newton's theory of universal gravitation. The reason for this was that he conducted an experiment that incorrectly suggested that Earth was elongated at its poles.

Interesting Facts

  • Giovanni Cassini had originally intended to study astrology but as time went on he turned to science and he later disclaimed his ideas of astrology.
  • When Cassini moved to France he became a citizen in 1673, changing his name to Jean-Dominique Cassini which he was known as for the rest of his life.
  • Cassini happened to also be an engineer and was hired by Pope Clement IX to work on management of the Po River and its flooding.
  • Giovanni led four successive generations of astronomers, his son Jacques Cassini, his grandson Cesar Francois Cassini, and his great-grandson Jean Dominique Cassini, all of who became Director of the Paris Observatory in their lives.
  • Cassini was the first to research the phenomenon known as the Zodiacal Light, a faint triangular glow seen in the late evening or early morning moonless sky and is the reflection of sunlight off fine particles of dust space.


Not much has been quoted concerning anything to do with Cassini. However there is a possibility he is the author of this quote, "A painting? You call that a painting? I could beat that with one hand tied behind me."