Black holes were once thought to be the monsters of the Universe, devouring everything around them in a frenzied cosmic feast. But now astronomers think that rather than being a space menace, black holes may be fundamental to the creation of galaxies.
Black holes are regions of space where gravity is so strong that not even light can escape, making them impossible to see. But we can see the stuff that is being sucked in to these massive cosmic vacuum cleaners. Anything that approaches a black hole is first torn apart by its immense gravitational force and then forms a flat rotating disc that spirals into the hole.