  The eclipse of the Sun of 1919 was fundamental in the development of physics
and earns a high place in the history of science. Several players took part in
this adventure. The most important are Einstein, Dyson, Eddington, the Sun, the
Moon, Sobral, and Principe. Einstein's theory of gravitation, general
relativity, had the prediction that the gravitational field of the Sun deflects
an incoming light ray from a background star on its way to Earth. The
calculation gave that the shift in the star's position was 1.75 arcseconds for
light rays passing at the Sun's rim. So to test it definitely it was necessary
to be in the right places on May 29, 1919, the day of the eclipse. That indeed
happened, with a Royal Greenwich Observatory team composed of Crommelin and
Davidson that went to Sobral, and that was led at a distance by the Astronomer
Royal Frank Dyson, and with Eddington of Cambridge University that went to
Principe with his assistant Cottingham. The adventure is fascinating, from the
preparations, to the day of the eclipse, the data analysis, the results, and
the history that has been made. It confirmed general relativity, and marked an
epoch that helped in delineating science in the post eclipse era up to now and
into the future. This year of 2019 we are celebrating this enormous
breakthrough
