Generically, such an object is called an active galaxy . If one of those beams happens to be pointed at Earth, we can see lots of light from across almost the entire electromagnetic spectrum, from radio waves to X-rays. Zoom In Artwork depicting binary quasars, two actively galaxies orbiting one another. Credit: NASA/ESA/Hubble/ESO/M. Kornmesser, adapted by Phil Plait We know that there are extremely massive black holes out there which may have grown to such enormous size when two big galaxies merge. The black holes fall toward each other, eventually orbiting each other and then, after billi...