Astronomers claim that a giant planet 124 light-years from Earth has provided the strongest evidence yet that alien life may be thriving outside our solar system.
Observations by the James Webb Space Telescope on a planet called K2-18 b appear to reveal chemical fingerprints of two compounds known to be produced only by life on Earth.
The detection of the chemicals, dimethyl sulfide (DMS) and dimethyl disulfide (DMDS), would not constitute evidence of alien biological activity, but it could come much closer to answering the question of whether we are alone in the universe.
"This is the strongest evidence yet for biological activity outside the solar system. We are very cautious. We have to ask ourselves whether the signal is real and what it means. Decades from now, we may look back on this moment and recognise that this was when a living universe came within reach. This could be a tipping point, where suddenly the fundamental question of whether we are alone in the universe is one that we can answer," said Professor Niku Madhusudan, an astrophysicist at the University of Cambridge who led the observations.
Others are more skeptical, and questions remain about whether the overall conditions on K2-18 b are favorable for life and whether DMS and DMDS, which are largely produced by marine phytoplankton on Earth, can reliably be considered biosignatures.
K2-18 b, a planet located in the constellation Leo, is nearly nine times more massive than Earth and 2,6 times larger, orbiting in the habitable zone of its star, a cool red dwarf less than half the size of the Sun. When the Hubble Space Telescope appeared to detect water vapor in its atmosphere in 2019, scientists declared it the "most habitable world known" outside the solar system.
The alleged water signal turned out to be methane in follow-up observations by Madhusudan's team in 2023. But, they argued, K2-18 b's profile was consistent with a habitable world, covered by a vast, deep ocean - a view that remains disputed.
Bonus video:
