Kepler's laws of planetary motion law" is what became the Second Law in the set of three; but Kepler did himself not privilege it in that way. Johannes Kepler published his first two laws about planetary motion in 1609, having found them by analyzing the astronomical observations of Tycho Brahe. Kepler's third law was published in 1619. Kepler had believed in the Copernican model of the solar system, which called for circular orbits, but he could not reconcile Brahe's highly precise observations with a circular fit to Mars' orbit—Mars coincidentally having the highest eccentricity of all planets except Mercury. His first law reflected this discovery.
Planetary and Space Science Planetary and Space Science Planetary and Space Science, published 15 times per year, is a peer-reviewed scientific journal established in 1959. It publishes original research articles along with short communications (letters). The main topic is solar system processes which encompasses multiple areas of the natural sciences. Numerical simulations of solar system processes are also conducted at ground-based facilities or on-board space platforms. The editor-in-chief is Angelo Pio Rossi (Jacobs University). It is published by Elsevier. Research that involves planetary and space sciences involves many disciplines, which is reflected by the scope of the journal. Celestial mechanics is part of these