Kepler and Brahe at work together c c German astronomer Johannes Kepler left with the Danish astronomer Tycho Brahe in Benatky Observatory near Prague while employed by emperor Rudolf II In Kepler published the results of Brahes calculations of the orbit of Mars which showed that the planet did not move uniformly in circles but in ellipses This celebrated work also outlined Keplers first and second laws governing planetary motion The formulation of his third law ten years later which connected the periods of revolution of the planets with their mean distances from the Sun completed his researches in dynamical astronomy From Vies des Savants Illustres Illustrated Lives of the Scientists by Louis Figuier Paris c