Astronomers believe Markarian 315, seen here in a Hubble Space Telescope image, is actually two galaxies that have collided, one of which has an active nucleus. The brighter of the two points of light is thought to be the nucleus of one of the galaxies. The very intense light that it radiates is believed to be generated by an accretion disk swirling around a huge black hole. The fainter point of light may be the core of a second galaxy.
