Is anybody out there? Scientists discover ‘strongest evidence’ so far of alien life
17 April 2025, 08:15 | Updated: 17 April 2025, 10:12
Scientists believe they have found the strongest evidence yet of extraterrestrial life in the form of a giant planet 124 light years from Earth.
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Astronomers working with the James Webb space telescope believe they have found the chemical fingerprints of two compounds that are known to be produced by life on the far-away planet K2-18 b.
The chemicals, dimethyl sulfide (DMS) and dimethyl disulfide (DMDS), do not prove alien life is out there, but could mark the largest step toward the discovery of extraterrestrials in decades.
“This is the strongest evidence to date for a biological activity beyond the solar system,” Prof Nikku Madhusudhan, an astrophysicist at the University of Cambridge who led the observations, said.
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“We are very cautious. We have to question ourselves both on whether the signal is real and what it means.
“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, where suddenly the fundamental question of whether we’re alone in the universe is one we’re capable of answering.”
K2-18 b is more than twice the size of Earth, with a mass nine times greater.
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It sits in the Leo constellation and orbits the habitable zone of its star, a red dwarf half the size of our sun.
When water vapour was discovered in the planet’s atmosphere six years ago, scientists declared it “the most habitable known world” outside of our solar system.
This so-called water was later discovered to be methane.
“The signal came through strong and clear,” Madhusudhan added.
“If we can detect these molecules on habitable planets, this is the first time we’ve been able to do that as a species … it’s mind-boggling that this is possible.”
The findings were published in The Astrophysical Journal Letters and indicate the concentrations of DMS and DMDS are thousands of times larger than what you would find on Earth.
“There may be processes that we don’t know about that are producing these molecules,” Madhusudhan said.
“But I don’t think there is any known process that can explain this without biology.”
Despite this discovery, actually proving that life exists out there is a very different proposition.
“Life is one of the options, but it’s one among many,” said Dr Nora Hänni, of the University of Berne.
“We would have to strictly rule out all the other options before claiming life.”
