In 1919, a total solar eclipse helped redefine gravity. Albert Einstein’s theory of general relativity, published in 1915, defined gravity as the influence of massive objects, like planets and stars, curving space around them. This was very different from the way Isaac Newton had defined gravity over 200 years earlier: Newton described an attracting force that kept planets and stars in orbit with each other. If Einstein was right, then light would also bend near massive objects. And in 1919, two British expeditions set out to test it by photographing a total solar eclipse. By comparing the position of stars with the sun in front of them and another with the sun elsewhere, Arthur Eddington and his team proved that the stars’ apparent positions moved during the eclipse. This was the first, but not the last time Einstein’s theory of general relativity was tested and proven, and Einstein became a celebrity overnight. He remained a pop culture icon for the rest of his life.