Yes, it's light years away. But planet K2-18 b may bring proof of alien life a step closer

A giant planet 124 light years from Earth has yielded the strongest evidence yet that extraterrestrial life may be thriving beyond our solar system, astronomers claim.

- Hannah Devlin

Observations by the James Webb space telescope of a planet called K2-18 b appear to reveal the chemical fingerprints of two compounds that, on Earth, are known to be produced only by life.

Detection of the chemicals, dimethyl sulfide (DMS) and dimethyl disulfide (DMDS), would not amount to proof of alien biological activity but could bring the answer on whether we are alone in the universe much closer.

"This is the strongest evidence to date for a biological activity beyond the solar system," said Prof Nikku Madhusudhan, an astrophysicist at the University of Cambridge who led the observations. "We are very cautious. We have to question ourselves both on whether the signal is real and what it means."

He added: "Decades from now, we may look back at this point in time and recognise it was when the living universe came within reach. This could be the tipping point."

Others are sceptical, with questions remaining about whether the conditions on K2-18 b are favourable to life and whether DMS and DMDS, which are largely produced by marine phytoplankton on Earth, can be reliably regarded as biosignatures.