Abstract

Why do Newton?s theory of gravitation and Einstein?s general relativity not manage to explain the ap-parent anomalous deceleration of certain spacecrafts, such as Pioneer 10, Pioneer 11, Ulysses, Galileo, and the anomalous apsidal motion of the binary stars DI Herculis? According to the present work (Combined Gravitational Action/Combgravaction), the problem raised by this question is mainly caused by the fact that the classical and relativistic theories of gravitation are founded on the same approximate expression of the Newton?s universal law of gravitation which, in reality, is not a single force in the common classical sense, but a resultant of two forces that make between them a very small angle , especially, when the test-mass is in motion outside the gravitational source. The smallness of that angle means that the resultant force and its two components are almost in superposition.