Watching telly the other night, and the subject of black holes came up. The merger of two black holes was first detected in 2015 by the Laser Interferometer Gravitational-Wave Observatory (LIGO) in the US. A professor from Glasgow University said the merged black hole was the size of Iceland. That’s equivalent to around five times Wales, for those of us who are more familiar with the latter measurement. Sounds pretty small to me, I always imagined black holes to be huge – and some of them are indeed massively bigger than this one. But the astonishing thing is that this one has the mass of 62 of our Suns. It’s very hard to envisualise such a phenomenon. There is nothing equivalent in our everyday comprehension. The Sun is 330,000 times the mass of Earth, so this black hole, the size of Iceland is equivalent to 20,460,000 planet Earths. Should we be worried?