Astronomers have found signs of alien life on a planet beyond our Solar System

Summary

Astronomers say they've found "the most promising signs yet" of chemicals on a planet beyond our Solar System that could indicate the presence of life on its surface. Using the James Webb Space Telescope, the team found a possible 'biosignature' – the potential fingerprint of life – within its atmosphere, although they say they're remaining "cautious", and that this isn't a confirmed detection. The chemicals detected are the same as those produced by marine-dwelling organisms on Earth. Credit: Photostock-Israel/Science Photo Library The team, led by the University of Cambridge in the UK, detected signs of dimethyl sulfide and dimethyl disulfide in the atmosphere of exoplanet K2-18b. This planet orbits its star in the habitable zone (sometimes called the Goldilocks Zone), which is the region around a star in which an orbiting planet might have conditions suitable for the emergence of life, such as the ability for liquid water to exist on its surface. K2-18b is 8.6 times as massive and 2.6 times as large as Earth and lies 124 lightyears away from our planet. An artist’s impression showing exoplanet K2-18b, its host star and an accompanying planet in this system. Credit: ESA/Hubble, M. Kornmesser. Credit: ESA/Hubble, M. Kornmesser Building a bigger picture This isn't the first study of exoplanet K2-18b. A 2023 study of K2-18b by the same team identified methane and carbon dioxide in the planet's atmosphere. This in itself was a huge discovery: the first time carbon-based molecules had been found in the atmosphere of an exoplanet – a planet beyond our Solar System – in the habitable zone. Astronomers say the 2023 results showed K2-18b could be a ‘Hycean’ planet, meaning a habitable world with a liquid ocean and a hydrogen-rich atmosphere. That earlier study found a tantalising hint of dimethyl sulfide and dimethyl disulfide, but this latest study has made a more promising detection. This graph shows detections of chemicals in the atmosphere of K2-18b by the James Webb S...