It’s the ultimate astronomers’ question: ‘Is there anybody out there?’ The quest to find out for sure is growing ever more sophisticated.

It was the call he’d always hoped for. Astrophysicist Chris Lintott was contacted at his Oxford home by an excited journalist with a question: “Is it true? Have we really discovered aliens?”

At that time, stargazers believed an oddly behaving star might be a sign of intelligent life. It transpired to be a false alarm – one of a few in living memory that have raised the hopes of scientists and space enthusiasts that we might not be alone in the universe (see False alarms and the unexplained, overleaf).

But Lintott – presenter of The Sky at Night and a professor at the University of Oxford who looks for astronomical anomalies using machine learning – remains excited. As the number of newly discovered exoplanets reaches 5,500 and will likely number trillions, he and a growing community are methodically searching the cosmos for signs of intelligent life.