Black holes have a fearsome reputation. They have imperilled a thousand stricken starship crews in the pages of science fiction, and the language used to describe them even in non-fiction often implies menace. In popular science, they ‘lurk’ at the centres of galaxies, waiting to ‘devour’ passing stars. I’m not sure this sort of imagery is justified, though it can be hard to avoid. A lot of the time black holes are passive, quiet beasts.
In the early hours of New Year's Day, billions of miles from any Earthly celebrations, the New Horizons space probe swung by a small and extremely distant lump of ice and rock. It’s known to cataloguers as (486958) 2014 MU69, but the New Horizons team call it 'Ultima Thule' after the ancient expression for a place at the edge of the known world.
Late one night in January 2005, I stood, freezing, in a car park on an industrial estate in Darmstadt, outside the European Space Operations Centre. The sky was beautifully clear, allowing the smattering of amateur astronomers present to point their telescopes at Saturn. A quick glance through a relatively modest instrument shows the orange disk of the planet, its system of rings and, visible as a point of light to one side, its largest moon, Titan.