Black holes are hard to find. They have such strong gravity that light can’t escape them, so scientists must rely on clues from their surroundings to find them.
When a star weighing more than 20 times the Sun runs out of fuel, it collapses into a black hole. Scientists estimate that there are tens of millions of these black holes dotted around the Milky Way, but so far we’ve only identified a few dozen.
This image from 2001 is an artist’s impression of a black hole accretion disk. Around many black holes is an accretion disk of material emitting energy as it falls into the black hole.
Image Credit: XMM-Newton, ESA, NASA
Editor: Yvette Smith