= Eddington experiment
{c}
{wiki}
The 1919 <solar eclipse> expeditions organized by <Frank Watson Dyson> and <Arthur Eddington> compared background-star positions near the obscured <Sun> with reference photographs. The optical train used a slowly rotating flat mirror to send the light into a horizontal photographic telescope. A smaller telescope at Sobral provided a separate set of plates. Focus and plate-scale changes had to be distinguished from the radial pattern predicted by <Schwarzschild light deflection>. The experiment therefore tested a spatial pattern and its amplitude, not merely whether a star image had moved.<A determination of the deflection of light by the Sun's gravitational field by Frank Watson Dyson and others>[1920 report of the 1919 observations]{ref} https://www.royalobservatorygreenwich.org/articles.php?article=1283[Equipment taken and the Sobral expedition: horizontal telescopes, tracking mirrors and reference plates]{ref}
Back to article page
