“I don’t gloss over the controversies and don’t pretend that we know more than we do about Mars,” says Simon Morden. “But we know enough to tell a story about how Mars started and how it may well end.”

In between these bookends of geological time, he says, “the most intriguing thing is that the planet we all thought we knew as a dead, cold, dry place is only like that sometimes”. By which he means that because of Mars’s orbital eccentricities, today “we could simply be looking at Mars while it is asleep. And the chances that it will wake up are genuinely high.”

He says the fact that we’re not recording active volcanoes or seeing vast expanses of water on the surface is a function of the era we live in and the moment at which we’re observing it.

Morden’s latest book – ‘The Red Planet: A Natural History of Mars’ –is careful to invite the reader away from the position of just looking at a passive, if somewhat conspicuous, feature of our night sky. The way...