Adam Frank

Last week, a team of astronomers led by the University of Cambridge professor Nikku Madhusudhan announced that they had found tentative evidence for a ‘biosignature’ embedded in the light from a distant planet. Scientists and non-scientists around the world tried to interpret the results. Was this it? Was this the moment when humanity could finally claim it had answered that ancient question: are we alone? As an astrophysicist involved in the search for life beyond Earth, I can tell you that the results were not that moment. But that doesn’t make them any less exciting.

Over the past three decades, astronomers have discovered planets orbiting Sun-like stars throughout the universe. This discovery ended 2,500 years of debate about whether worlds existed beyond our solar system, but it came with a shock. The most common kind of planet in the universe is the type of world that doesn’t exist in our small corner of the cosmos: what astronomers call ‘Super-Earths’ and ‘Sub-Neptunes’, planets with much greater masses than ours and which could, in theory, sustain life. Astronomers concluded a little over a decade ago that every star in the night sky hosts a family of worlds. Importantly for the search for life, one in five of those stars will have a planet in the ‘Goldilocks’ zone (sometimes referred to as the ‘habitable zone’).

When Nasa launched the James Webb Space telescope on Christmas Day last year its goal was to shed light on the wonders of the universe. It’s delivering on that promise: since the summer we’ve had a steady stream of stunning images of dying stars, distant planets and colliding galaxies. Researchers expected the telescope’s data would support the Big Bang theory. But it has captured images so far back in time, revealing the existence of galaxies so old, that the very origins of the universe have instead been called into question. ‘I find myself lying awake at three in the morning wondering if everything I’ve ever done is wrong,’ said Allison Kirkpatrick, an astronomer at the University of Kansas, after seeing the first images from the James Webb telescope.