the Solar System in the past, passing within 29 light-years distant around 237,000 years ago. At this range, it would have shone at apparent magnitude −0.82, comparable to Canopus today. In a 1960 paper, American astronomer Olin J. Eggen concluded that Capella was a member of the Hyades moving group, a group of stars moving in the same direction as the Hyades cluster, after analysing its proper motion and parallax. Members of the group are of a similar age, and those that are around 2.5 times as massive as the Sun have moved off the main sequence after exhausting their core hydrogen reserves and are expanding and cooling into red giants. Stellar system There are several stars within a few arcminutes of Capella and some have been listed as companions in various multiple star catalogues. The Washington Double Star Catalog lists components A, B, C, D, E, F, G, H, I, L, M, N, O, P, Q, and R, with A being the naked-eye star. Most are only line-of-sight companions, but the close pair of red dwarfs H and L are at the same distance as the bright component A and moving through space along with it. Capella A is itself a spectroscopic binary with components Aa and Ab, both giant stars. The pair of giants is separated from the pair of red dwarfs by 723". American astronomer Robert Burnham Jr. described a scale model of the system where Capella A was represented by spheres 13 and 7 inches across, separated by ten feet. The red dwarfs were then each 0.7 inch across and they were separated by 420 feet. At this scale, the two pairs are 21 miles apart. Capella A Capella A consists of two yellow evolved stars that have been calculated to orbit each other every 104.02128 ± 0.00016 days, with a semimajor axis of 111.11 ± 0.10 million km (0.74272 ± 0.00069 AU), roughly the distance between Venus and the Sun. The pair is not an eclipsing binary—that is, as seen from Earth, neither star passes in front of the other. The orbit is known extremely accurately and can be used to derive an orbital parallax with far better precision than the one measured directly. The stars are not near enough to each other for the Roche lobe of either star to have been filled and any significant mass transfer to have taken place, even during