In September 2022, a small spacecraft crashed into an asteroid called Dimorphos. The $330 million double asteroid redirection test (DART) probe was destroyed in an instant, to the relief of everyone at Mission Control. They were trying to see if it was possible to nudge an asteroid off course as a way of saving our planet one day. The experiment worked. The science journalist Robin George Andrews was there to see the show.

His book runs through the modern history of planetary defence, which can be said to have started in 1994, when Comet Shoemaker-Levy 9 collided with Jupiter. The comet had been tracked well in advance; telescopes around the world were able to see the scars it left on Jupiter’s surface. Had the comet hit Earth instead, it could have been the end of all of us. Cosmic cataclysm suddenly seemed a real possibility.

Comets are lumps of ice and rock that wheel in from the outer edges of the solar system. Asteroids are made of similar stuff but mostly reside between the orbits of Mars and Jupiter. Either type hitting Earth could be bad news. Both possibilities were played out in ‘two seriously