CAPELLA, the fifth or sixth brightest star in the sky, and the brightest star in the constellation Auriga (q.v.) hence its alterna tive name a Aurigae. It was found to be a spectroscopic binary by Newall and Campbell (see STAR), and the separation of its two components (q.v.) was first directly measured in 1919 with Mich elson's interferometer (q.v.) in conjunction with the ioo-in. tele scope on Mt. Wilson. The spectrum (see SPECTROSCOPY) of Capella closely resembles that of the sun.