A strong radio source approximately 10⁹ l.y. away in the constellation Cygnus, identified with a giant elliptical galaxy of 15th magnitude. Cygnus A is the brightest extragalactic radio source. It is a classical radio galaxy with prominent radio-emitting lobes on either side of the central source, fed by faint, narrow jets. The optical parent galaxy, first identified in 1952, has an unusual structure which was originally interpreted as two spiral galaxies in collision. Although this model was subsequently rejected, it remains possible that giant elliptical galaxies such as Cygnus A may have arisen from the merger of smaller galaxies.