Astronomers believe supermassive black holes probably lurk in the centers of most large galaxies. These gargantuan black holes can gather swirling disks of material around them as their gravity attracts stars and gases. In some cases, these disks can emit vast amounts of light and even shoot huge jets of matter into space. The center of such an eventful galaxy is called an active galactic nucleus, or AGN.
Our own Milky Way seems to have a relatively calm center, but astronomers suspect this wasn’t always the case.
