Title page of Kepler's New Astronomy (Astronomia Nova). The book was completed in and published in Linz in 1609. Buried deep in this at times very mystical book are Kepler's first formulation of his first and second Laws of planetary motion, which in modern parlance can be stated as follows:
Kepler, J. 1609, Astronomia Nova, trans. W.H. Donahue 1992, Cambridge University Press.
Stephenson, B. 1987, Kepler's physical astronomy, [1994 reprint, Princeton University Press].
-Written and last revised 20 December 1997 by paulchar@ucar.edu.