Johannes Kepler (1571-1630)
Astronomia nova ΑΙΤΙΟΛΟΓΗΤΟΣ : sev physica coelestis, tradita commentariis de motibvs stellæ Martis
[Prague], 1609.

In this work Kepler established that Copernicus’s sun-centred system explained observed planetary motion, which he also showed to be in elliptical orbits From today’s perspective we appreciate that this work that began the full scientific treatment of astronomy. From observations of Mars Kepler established that both the Aristotelian and Tychonic systems failed to account for planetary motions as the Copernican system could, also showing that the planets moved in elliptical orbits and propounding that they were independent physical objects and were not moving in individual celestial spheres.

M.7.40, pp. 284-285