Photograph of the solar eclipse of 29 May 1919 taken by Arthur Eddington and Edwin Cottingham on the island of Principe.
Photograph of the solar eclipse by Arthur Eddington and Edwin Cottingham, Principe, 29 May 1919 [Image credit: Royal Astronomical Society]

On 29 May 2019 exactly 100 years will have passed since the confirmation of Einstein's General Theory of Relativity, an event that fundamentally changed our understanding of physics and astronomy.

Astronomer Sir Arthur Eddington organised two expeditions to observe a total solar eclipse - when the Moon appears to completely block out the Sun - with teams of scientists travelling to the island of Principe off the coast of west Africa and to Sobral in Brazil. This joint expedition was led by the Royal Astronomical Society and the Royal Society, with staff and equipment from the Royal Observatory Greenwich, and the universities of Cambridge and Oxford.

Photographs taken during the eclipse showed the apparent deflection of stars from their normal position, confirming Einstein’s theory.

Here you can find out about events and activities taking place around the world to celebrate the centenary of the eclipse, in Principe, Sobral, the Observatory Science Centre in the UK, and elsewhere. You can also learn more about the eclipse expeditions and General Relativity.

This website has been created by the organisations leading the 2019 eclipse celebrations and those which were involved in the joint expedition in 1919.


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