*…show more content…*

Using his collected information Kepler discovered that the orbit of Mars was an ellipse. In 1609 he published Astronomia Nova, delineating his discoveries, which are now called Kepler's first two laws of planetary motion. And what is just as important about this work, "it is the first published account wherein a scientist documents how he has coped with the multitude of imperfect data to forge a theory of surpassing accuracy" (O. Gingerich in foreword to Johannes Kepler New Astronomy translated by W. Donahue, Cambridge Univ Press, 1992), which today's is known as the Scientific

*…show more content…*

The reason that the orbit of Mars was particularly difficult was that Copernicus had correctly placed the Sun at the center of the Solar System, but had an error in assuming the orbits of the planets to be circles. After a long struggle, in which he tried mightily to avoid his eventual conclusion, Kepler was forced finally to the realization that the orbits of the planets were not the circles demanded by Aristotle and assumed implicitly by Copernicus, but were instead ellipses. Kepler created the Law of Planetary Motion which has three laws that state the Sun is not at the center of the ellipse, but is instead at one focus, the line joining the Sun and planet sweeps out equal areas in equal times, so the planet moves faster when it is nearer the Sun and, the ratio of the squares of the revolutionary periods for two planets is equal to the ratio of the cubes of their semimajor