Some six months after the Great War of 1914-18 ended, Arthur Eddington travelled at the head of a team on a scientific expedition to the island of Principe off the coast of Equatorial Guinea in West Africa. He headed one of the two teams of astronomers assigned by a Joint Permanent Eclipse Committee of the Royal Society and the Royal Astronomical Society of Britain to observe and record photographically the full solar eclipse scheduled to take place on May 29, 1919.
At the time under Portuguese rule, Principe was selected as one of the two sites – the other was Sobral in the Brazilian Nordeste – from where the total solar eclipse and its full effect could be best observed. The expedition was proposed by Eddington, a rising star among British astronomers, to test Einstein’s general theory of relativity published in the middle of the Great War.
Eddington’s expedition to Principe a century ago tested and confirmed Einstein’s general theory of relativity as the single most outstanding scientific achievement in history by one individual. For more than two centuries Newton’s theory of gravitation, of space and time and motion, had stood as the definitive theory in explaining the mechanics of the universe, and had marked a paradigmatic shift in thinking that characterized the birth of the modern world as Newtonian.