Precession of the perihelion of Mercury's orbit

The precession of the perihelion of Mercury's orbit is calculated using the Laplace-Runge-Lenz vector. An approximate calculation that assumes the orbits of the perturbing planets are circular and coplanar with Mercury's orbit is within 4.4% of the correct value. A complete calculation that uses the correct elliptical orbit and orientation for each of the perturbing planets is then presented. The precession due to a perturbing planet is proportional to the mass of the planet and is approximately inversely proportional to the cube of its semimajor axis. (c) 2005 American Association ofPhysics Teachers.