Rain of Giant Gas Clouds Create Active Galactic Nuclei

Galaxies like our own were built billions of years ago from a deluge of giant clouds of gas, some of which continue to rain down. Now new calculations tie the rain of giant clouds of gas to active galactic nuclei (AGN), the extremely bright centers of some galaxies. If a gas cloud with millions of times more mass than our Sun wanders too close to the center of a galaxy, it can either be consumed by the supermassive black hole that lurks there or, through shocks and collapse, give birth to new stars.