Capella. First of two images showing the motions of the double star system called Capella. The two stars are each about three times the mass of the Sun, and have a mutual orbital period of 104 days. Just 45 light years from Earth, the stars are so close together that conventional telescopes cannot resolve the two elements. To most observers, the system appears to be a single star (also called alpha Aurigae), the seventh brightest in the sky. This image was made at a wavelength of 830 nanometres on 13 September 1995 using the COAST optical interferometric telescope at Cambridge, UK. Compare with image ref R620/171.