The Eclipse That Proved Einstein Was Right

In May 1919, British astronomer Arthur Eddington organised an expedition with the Astronomer Royal, Frank Dyson, to observe a total solar eclipse and put Einstein’s new theory of general relativity to the test. Eddington was one of the few scientists who understood Einstein’s theory when it was published, and one of the few British pacifists who would listen to a German scientist during the Great War.

According to general relativity, light bends around massive objects, a phenomenon that should be visible when the Sun passes in front of faraway stars, if only its brightness didn’t block out the twinkle of the stars. The total eclipse provided a perfect opportunity: for once, the light of the Sun would be blocked (by the Moon), and its surrounding stars should appear further apart from each other than they normally do — if Einstein great theory was right, of course.