advance of the perihelion
advance of the perihelion
The gradual movement of the perihelion of a planet's elliptical orbit in the same direction as that of the planet's orbital motion. This advance results from the slow rotation of the major axis of the planet's orbit due to gravitational disturbances by other planets and to the curvature of spacetime around the Sun. The small contribution from the curvature of spacetime was predicted by Einstein's general theory of relativity.The value of this relativistic contribution toward the advance of the perihelion of Mercury is about 43 arc seconds per century. This agrees almost exactly with the discrepancy between the experimentally determined value for the advance and that predicted by classical Newtonian mechanics. It was therefore an important confirmation of general relativity. Recent measurements of the advance of the perihelia of Venus and Earth have also been very close to Einstein's predicted values for those planets.