Kepler's First Law of Planetary Motion
Law of Elliptical Orbits
Orbit Parameters
Kepler's First Law
Law of Orbits: All planets move in elliptical orbits with the Sun situated at one of the foci.
The ellipse is defined by its semi-major axis (a) and eccentricity (e). The closest point to the Sun is called perihelion, and the farthest point is aphelion.
Eccentricity ranges from 0 (perfect circle) to nearly 1 (highly elongated ellipse).
