On April 10 2019, the Event Horizon Telescope (EHT) Collaboration revealed the first picture of a black hole. The object is at the centre of a galaxy known as M87, about 55 million light-years away. The iconic ring structure instantly became one of the most recognised scientific images of the modern era. It showed a black hole “shadow” outlined by light from swirling hot gas – just as predicted by Einstein’s theory of general relativity.