Author: David Parkinson, Research Scientist in Astrophysics, The University of Queensland

Black holes don’t have many identifying features. They come in one colour (black) and one shape (spherical). The main difference between black holes is mass: some weigh about as much as a star like our Sun, while others weigh around a million times more. Stellar-mass black holes can be found anywhere in a galaxy, but the really big ones (known as supermassive black holes) are found in the cores of galaxies. These supermassive behemoths are still quite tiny when seen in cosmic perspective, typically containing only around 1% of their host galaxy’s mass and extending only to a millionth of…