Astronomia nova [New Astronomy]

Kepler’s Astronomia nova (New Astronomy) provided strong arguments for heliocentrism and contributed valuable insight into the movement of the planets. It is regarded as one of the most important works of the Scientific Revolution.

Astronomia Nova introduced the first two of Kepler's three laws: first, that each planet moves on an elliptical path, with the Sun at one focus; and second, that a line connecting any planet to the Sun sweeps out area at a constant rate — which implies that a planet moves faster when it is nearer the Sun. Kepler was the first to realize that orbits are better described by ellipses traversed at nonuniform speed than by combinations of 'perfect' circular motions on which orbits had hitherto been modelled. His weaving together of observations and mathematical models into a physical theory was a vanguard for future studies. Kepler was an early champion of the application of reason to our understanding of the Universe. He wrote in his introduction to Astronomia Nova: “I prove philosophically not only that the Earth is round ... not only that it is contemptibly small, but also that it is carried along among the stars.”