Celebrating the 1919 Eclipse at Principe

In May 1919, Sir Arthur Eddington took part in an historic eclipse expedition, organised by the Royal Astronomical Society, to the African equatorial island of Príncipe. By comparing the positions of stars in the Hyades star cluster at the time of eclipse, with those determined earlier, the gravitational deflection of 1.75 arcsec predicted by Einstein's theory of relativity was satisfactorily verified. Historians recognise this expedition as a major achievement of 20th century science, conducted in part by one of the UK's most distinguished astronomers, whose outcome was largely responsible for Einstein's fame (Stanley 2007).

Although neither Einstein nor Eddington foresaw any practical applications for gravitational lensing (the deflection of light rays by massive objects), 90 years later it has emerged as the most promising probe of our Universe.

We will establish on São Tomé and Príncipe a celebration of 90 years of gravitational lensing. The main goal is to explain, for the benefit of both its citizens and visitors, the importance of Eddington's expedition and how gravitational lensing is shaping our view of the Universe. This will establish, on the one hand, local recognition of the importance of astronomy, particularly for young people. On the other hand, it will help preserve a site of significant cultural value and create an additional point of attraction beneficial to the emerging tourist industry.