On a giant exoplanet, 124 light-years from Earth, the strongest signs yet of possible biological activity beyond our solar system have been detected, according to observations by the James Webb Space Telescope.
Astronomers have detected on the exoplanet K2-18 b traces of two chemical compounds – dimethyl sulfide (DMS) and dimethyl disulfide (DMDS) – which, on Earth, are produced exclusively by life forms such as marine phytoplankton.
"Perhaps the turning point in the search for life"
“This is the strongest evidence to date for possible biological activity beyond our solar system,” Professor Nikku Madhusudhan, an astrophysicist at the University of Cambridge, who led the research team, told the Guardian.
"We are very cautious. We have to question both the validity of the signal and what it might mean," he added.
According to him, "perhaps in the future we will look back on this moment and recognize that it was the turning point – where the question 'are we alone?' could be answered."
The doubters and the open possibilities
Although the detection of the compounds is statistically significant (with a probability of only 0,3% being a random event), it is not sufficient on its own to prove the existence of life.
Dr. Nora Hänni, a chemist at the University of Bern, stressed that DMS has also been detected on comets without traces of life, while other researchers emphasize that the conditions on K2-18 b remain controversial: it could be a planet with oceans, but also a gas planet, or even a world of magma.
A planet with a past of promise
K2-18 b, located in the constellation Leo, has almost nine times the mass of Earth and is about 2,6 times larger, orbiting within the habitable zone of its star – a red dwarf with half the mass of the Sun.
In 2019, the Hubble Space Telescope appeared to detect water vapor in its atmosphere, with scientists calling it “the most habitable world known.” But later analyses in 2023 showed that the signal likely came from methane, sparking new questions and the theory of a deep ocean.
James Webb's signal: Clear and strong
As the planet passed in front of its star, James Webb detected a dip in specific wavelengths, consistent with absorption by DMS and DMDS.
The presence of the molecules could also be explained by extremely rare cosmic impacts, volcanic activity, or chemical reactions in hydrothermal vents, but all of these alternatives remain hypothetical.
Despite the disagreements, scientists agree that this is a major leap in the search for extraterrestrial life, even if it does not constitute proof. If this discovery proves reliable and is confirmed by future observations, then we may be closer than ever to answering the ancient question: “Are we alone in the universe?”
Source: protothema.gr
