Johannes Kepler

German astronomer and mathematician., 1571-1630. In He was professor of mathematics at Graz (159398) and court mathematician to Holy Roman Emperor Rudolf II. In 1596 he wrote Mysterium cosmographicum, which led to exchanges with Galileo and Tycho Brahe. His Astronomia nova (1609) contained the first two of what became Kepler's Laws; the third law appeared in 1619 in his Harmonice mundi. These laws were the result of calculations based on Brahe's accurate observations, which Kepler published in the Tabulae Rudolphinae (1627).