# Johannes Kepler

German astronomer and mathematician., 1571-1630. In He was professor of mathematics at Graz (1593–98) 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).

### References

- Kepler, Johannes,
*Astronomia nova,* 1609.
- Kepler, Johannes,
*Mysterium cosmographicum,* 1596.
- Koestler, Arthur,
*The Watershed,* New York: Doubleday, 1960.
- J. Trefil and R. M. Hazen,
*The Sciences: An Integrated Approach,* pp. 36-37.