In this video I will explain why there is a 43” per century discrepancy from the observed and calculated precession of Mercury (approximately 5600' per century). We know, from Einstein's general relativity, time runs slower in the Sun's gravitational field. And from special relativity we also know time slows when something moves very fast. In 1859, Urbain Le Verrier estimated the discrepancy to be 38” per century. And in 1882 Simon Newcomb re-estimated the discrepancy to be 43” per century.