All of a sudden the interstellar space around our solar system – the enormous gulf that separates us from the nearest stars and their planets – is starting to look congested. There is traffic out there: mysterious objects on their way between solar systems.

The first time we spotted one of these interlopers was in 2017, when ‘Oumuamua – a long, thin thing about the size of the Shard skyscraper – pulled off the unusual trick of accelerating as it was heading away from the sun. ‘Oumuamua is almost certainly a piece of weird, attention-seeking rock rather than an alien spacecraft, but by the time we realised how curious this comet was, it was already speeding beyond the reach of any rockets.

As a second interloper, comet Borisov, swims into our ken, complete with a cometary tail that could give clues to the biochemistry of another star, it’s worth remembering the vastness of the distances it has covered.

If you have room in your life for only one gorgeous, all-encompassing and satisfyingly detailed reference work on our place in the cosmos, the DK Illustrated Encyclopedia of the Universe is one of the best out there, and – edited by astronomer royal Sir Martin Rees – it’s got impeccable credentials. Swoon over the illustrations and marvel at the scale of things. Astronomy reference books are always slightly out of date, such is the pace of new discoveries, but this book is still rarely off my desk.

In the excitement surrounding the discovery of ‘Oumuamua, much was made of the apparent similarities with the object at the heart of Arthur C Clarke’s 1973 novel Rendezvous With Rama. Initially thought to be an asteroid, the titular Rama turns out to be a long, hollow alien spacecraft. Like ‘Oumuamua, it just happens to be passing through – but in Rama’s case, an expedition is just about feasible. Clarke’s novel is dated in some regards, but in terms of presenting the pure thrill of discovery it remains one of the most compelling novels in the SF canon.

A significant triumph in recent astronomy has been the detection of gravitational waves, finally achieved by an international consortium using immensely precise (and huge) laser interferometers. But the work to reach this discovery began a century ago, and encompasses a huge cast of heroes and dreamers – and its share of failure. In Black Hole Blues astrophysicist Janna Levin has written the definitive account of this grand quest, and it’s as insightful about the human protagonists in this story as it is about the mind-bending physics of black holes and warped spacetime.

Interstellar visitors need not be as large as Rama to wreak transformation, especially if there is intelligence at work. In Tade Thompson’s Rosewater, which won 2019’s Arthur C Clarke award, an alien construct hits London, then tunnels all the way through to Nigeria, eventually emerging and releasing spores that begin to affect human neurological functioning. Thompson continued the story with Rosewater Insurrection, with the final part of the trilogy, Rosewater Redemption, published this year.

And while it might not be interstellar in origin, the close approach of a comet of another kind provides the narrative mainspring for Liz Williams’s forthcoming Comet Weather, a brilliant, genre-defying novel of astronomy, Somerset, haunted sisters, Traveller lore and witchcraft. Read it as Borisov waves goodbye to our solar system, on its long, lonely haul back into interstellar darkness.

• Revenger by Alastair Reynolds is published by Gollancz.