The Black Star is Coming - Terral

A binary star is a star system consisting of two stars orbiting around their common center of mass. The more massive star is called the primary and the other is its companion star, comes /'ko?mi?z/, or secondary. Systems of two, three, four, or even more stars are called multiple star systems. These systems, especially when more distant, often appear to the unaided eye as a single point of light, and are then revealed as double (or more) by other means. Research over the last two centuries suggests that half or more of visible stars are part of multiple star systems.