The relativistic enlargement of the apparent radius of the sun

The angular diameter 2THETA of the sun increases by the Einsteinian bending of light rays only about ΔTHETA approximately (2fM/c2R) THETA approximately 4 . 10-6 THETA (with the mass M and the radius R of the sun). This small enlargement - firstly remarked by Eddington -agrees with the non-euclidean geometry on the surface of the sun according to the Schwarzschild metrics. Generally, the enlargement 2ΔTHETA of the apparent angular diameter of a star (with the mas Msub(S)) is the Einstein bending of the star-light by the gravitation potential of this star in the distance asub(S) between the star and the observer: 2ΔTHETA approximately (4fMs/c2as). (author)