1882-1944

English astronomer who was one of the founders of modern astrophysics. Eddington showed that, to avoid collapse, the outward gas and radiation pressure of a star must equal its inward gravitational pull. This placed an upper limit of 50 solar masses on stable stars. Cepheid variable pulsation, he argued, was due to a star's instability. Eddington also established the mass luminosity law and led the 1919 solar eclipse expedition, which confirmed the gravitational bending of light.