An experiment that Einstein did in 1915 to prove General Relativity was correct was to calculate the angle through which starlight signals that just graze the sun would be bent in a solar eclipse and he got 0.00049°. The detection of an angle at this degree was possible back then. So Sir Arthur Eddington, a well-known astronomer and secretary of the Royal Astronomical Society set off to the island of Principe off the coast of West Africa to test Einstein's prediction during the solar eclipse of May 29, 1919. On November 6, 1919, after 5 months of analysis of photographs taken during the eclipse at Principe, it was announced at a meeting of the Royal Society and the Royal Astronomical Society that Einstein's prediction on the angle of the light caused by gravity had been confirmed to be true.
Source is from The Elegant Universe by Brian Greene.