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How did the 1919 solar eclipse test Albert Einstein’s prediction about bending light?

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Portrait of Albert Einstein in a suit and tie, looking slightly to the side with a neutral expression. — Albert Einstein Albert Einstein developed the special and general theory of relativity, which recast gravity as a bending in space-time.

Albert Einstein’s general theory of relativity predicted that gravity would bend the path of light passing near a massive body, such as the Sun, by approximately 1.75 arc seconds. Under normal conditions, this effect is impossible to observe because the Sun’s brightness obscures nearby stars.12

To test this, British astronomers Frank Dyson and Arthur Eddington organized two expeditions to observe the total solar eclipse on May 29, 1919—one to Sobral, Brazil, and another to the island of Príncipe. By photographing the field of stars near the Sun during the darkness of totality and comparing those images to reference photographs taken at night, the teams could measure the displacement of the stars' apparent positions caused by the Sun's gravitational field.123

The combined results from the expeditions supported Einstein’s prediction, providing critical evidence for his theory. This successful test brought Einstein international fame and helped establish him as a leading figure in modern physics.142