Perihelion Shift of Mercury (rewritten, from my post, posted on Sep 16 or around) （クリ)
There is a figure of Mercury and its orbit. Mercury is drawn as a single point. But actually, Mercury has a size, and this size will slightly increase magnitude of gravity and centrifugal force of Mercury. Now, limit our consideration to half of orbit from perihelion to aphelion. Increase in gravity will shift aphelion in the direction of revolution. On the other hand, increase in centrifugal force will shift aphelion in the opposite direction of revolution. In increase, gravity will exceed.
