Giovanni Domenico Cassini , also known as Jean-Dominique Cassini , ( June 8 , 1625 â `` September 14 , 1712 ) was an Italian-French astronomer , engineer and astrologer . For his French-born great-grandson , see Jean-Dominique Cassini . Giovanni Domenico Cassini ( June 8 , 1625 â `` September 14 , 1712 ) was an Italian\/French mathematician , astronomer , engineer , and astrologer .