ABSTRACT
Among many exact solutions of the A. Einstein field equations known at present only a few solutions are used in astronomy, mainly in relativistic cosmology and relativistic astrophysics. In relativistic celestial mechanics it is possible to use only three rigorous solutions related to the case of one gravitating body. For cosmology and relativistic astrophysics the internal Schwarzschild problem, that is the determination of the gravitational field inside a body, is of no less importance. But for practical purposes of relativistic celestial mechanics this solution is of no interest. The Schwarzschild solution is the exact solution of the field equations. For the real bodies of the Solar System the gravitational radii are extremely small as compared with their linear sizes and all these interesting cases cannot be realized in practice. For relativistic celestial mechanics it is sufficient to deal with an approximate solution.
