First Experimental Test of General Relativity
Measurement of positions of stars whose light passes close to the Sun on its way to the Earth.
Expeditions organized to Brazil & Africa in 1919 to make measurements during solar eclipse.
(Great fanfare and anticipation - first joint scientific expedition of the countries who had just concluded World War I in 1918.)
Results: measure ? =1.64” arc in agreement with Einstein’s prediction of 1.75” arc.
More precision recently with radar.