The Invariable Plane of our solar system passes through the center of gravity of the system and is independent of the mutual perturbations of the planets. It is called 'invariable' because it remains unaltered, regardless of any and all motions within the planetary system. It is a plane through the center of mass, perpendicular to the orbital angular-momentum factor. This factor is made up of the angular momentum arising from orbital revolutions and from axial rotations.

As one planet decreases its eccentricity and inclination (over very long time periods), one or more orbits must at the same time be increasing their eccentricities and inclinations, whereby the total amount of eccentricity and inclination remains constant. Jupiter and Saturn largely determine the invariable plane, since they are the largest and heaviest of the planets. There has been some thought given to using the invariable plane as a fundamental reference plane on which to study planetary configurations. The center of mass of the solar system moves, with respect to the inertial system of reference, in a straight line with constant speed through space in a 250-million-year orbit or circle around the galactic center. The northern node of the invariable plane to the ecliptic is 107°03'46.99" in longitude (1950.0) with an inclination of 1°34'50" to the ecliptic plane. Thanks to Charles A. Jayne, Jr. for his research on this subject.

Copyright (c) 1997-99 Michael Erlewine