Chris Lintott

There’s a long history of astronomers looking for signs of life on Venus. Throughout the 19th century and into the 20th, reports circulated of a mysterious glow, known as the Ashen Light, which sporadically appeared on the planet’s night side. Could it be a product of civilisation, perhaps the glow of vast ritual bonfires breaking through the thick clouds that were known to blanket the planet? Later writers speculated about vast underground cities, or intelligent creatures who made the most of the thick atmosphere for aerial acrobatics. When spacecraft finally visited our neighbouring planet, in the 1960s, dreams of life on Venus receded. A runaway version of the greenhouse effect has changed what may once have been a pleasant world to a decent approximation of hell; the surface temperature is hot enough to melt lead, the pressure on the ground high enough to crush a visiting astronaut, and those thick clouds are mostly sulphuric acid. A few dreamers still wrote of floating cities in Venusian clouds, but attention turned to Mars as the best bet for searching for past or present life. Until this week, that is.

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.