Cygnus A

Cygnus A, most powerful cosmic source of radio waves known, lying in the northern constellation Cygnus about 500,000,000 light-years (4.8 × 10²¹ km) from Earth. It has the appearance of a double galaxy. For a time it was thought to be two galaxies in collision, but the energy output is too large to be accounted for in that way. Radio energy is emitted from Cygnus A at an estimated 10⁴⁵ ergs per second, more than 10¹¹ times the rate at which energy of all kinds is emitted by the Sun. The source of the energy of Cygnus A remains undetermined.