Laplace plane

The Laplace plane, named after Pierre-Simon Laplace, is defined as the mean plane occupied by the orbit of a satellite during a precession cycle. In other words, the plane normal to the orbital precession pole of the satellite.It is used to describe the orbits of satellites of gas giants. The "plane" is in fact a non-planar surface whose orientation in space is somewhat warped as distance from the planet increases. Roughly, for the satellites orbiting very close to the planet the Laplace plane is the planet's equatorial plane (being dominated by the planet's oblateness), while with increasing distance it warps or tilts until it approaches the orbital plane of the planet for its outer satellites (being dominated by the Sun). There are, however, some appreciable deviations from this rule. For example, the Laplace planes for the satellites of Neptune are strongly influenced by the largest moon Triton, while for the outer satellites of Jupiter (Ananke, Pasiphaë and the others), the perturbations induced by Saturn are sufficiently important to make the Laplace plane deviate from the orbital plane.