 When light comes close to the sun, the sun's gravity bends it inward. This makes the star look like it's further away from the sun in the sky than it really is. Both Einstein's and Newton's gravitational theories predicted this. But the theories predicted different values for the amount light would bend. Einstein suggested that a solar eclipse could be used to find the exact number. In 1919, a solar eclipse was slated to occur with the sun silhouetted against the Hyades star cluster, the nearest open cluster to our solar system. Here's the Hyades star configuration with some of the brightest stars identified. The British astrophysicist Arthur Eddington took up positions off the coast of Africa and Brazil and simultaneously measured the cluster's light as it brushed past the sun. The images were then superimposed on top of an image taken at night earlier in the year. When the eclipse and night images were compared, a gap was found. And when the gap was measured, it confirmed that Einstein's prediction was correct.