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Motion of the perihelion of Mercury

The position of the perihelion of Mercury changes with time, the axis of the orbit slowly rotates. (see Figure 1). Originally this was thought to be due to the combined gravitational pull of all the other planets but this predicted value was found to be wrong by about 43" per century. The difference is explained by the general theory of relativity. This divergence from theory was then explained by the existence of a gravitational attraction of a then undiscovered planet called Vulcan between Mercury and the Sun.

The true explanation was given by the General theory of Relativity.

© Keith Gibbs 2011