New evidence from the James Webb Space Telescope suggests the exoplanet K2-18b may host life, offering hope for extraterrestrial discovery—but skepticism remains.
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| The detection of life-related chemicals on K2-18b offers the strongest evidence yet of extraterrestrial life, though scientific uncertainty still clouds the findings. Image: Cambridge |
CAMBRIDGE, UK — April 17, 2025:
A promising breakthrough in the search for extraterrestrial life has emerged from the depths of space, with new findings from NASA’s James Webb Space Telescope (JWST) suggesting that the exoplanet K2-18b might harbor signs of life. This marks the second time chemicals associated with biological processes have been detected in the planet's atmosphere—an exciting step forward in our quest to understand if life exists beyond Earth, reads an ENCA post.
K2-18b, a planet located 700 trillion miles away and 2.5 times the size of Earth, has become the focal point of this new discovery. A team of scientists from Cambridge University, led by Professor Nikku Madhusudhan, identified dimethyl sulphide (DMS) and dimethyl disulphide (DMDS)—gases that, on Earth, are produced by marine plankton and bacteria. The detection of these molecules during a single observation surprised even the researchers, who found concentrations thousands of times higher than those found on Earth.
"This is the strongest evidence yet that there is possibly life out there," Professor Madhusudhan said. "I am confident that we will be able to confirm this signal within one to two years."
While the findings are groundbreaking, there are significant scientific hurdles yet to overcome. The data currently holds a "three sigma" confidence level—99.7% certainty, far from the 99.99999% (five sigma) required for definitive proof in the scientific community. This means that while the discovery is promising, it is not conclusive enough to claim with certainty that life exists on K2-18b.
Professor Catherine Heymans, Scotland’s Astronomer Royal, who is independent of the study, warned that even if the results were confirmed with five sigma certainty, the origin of the gases would still be in question. "On Earth, these gases are produced by microorganisms, but we can't rule out non-biological explanations on an alien world," she said. "The universe contains many unknowns, and we need to consider all possibilities."
In light of this, the Cambridge team is working with other research groups to explore whether DMS and DMDS could be produced through non-biological processes. Despite these uncertainties, the presence of such molecules raises exciting possibilities about the conditions on K2-18b.
The debate over the planet’s nature adds another layer of complexity to the study. Some researchers believe that K2-18b may be covered by a vast ocean, inferred by the absence of ammonia in its atmosphere. Others, however, suggest that the planet could be a gas giant with no surface or even a molten rock world, which would be inhospitable to life.
Further complicating matters, Dr. Nicolas Wogan from NASA’s Ames Research Center has proposed that K2-18b might not have a surface at all, arguing that it could be a mini gas giant. Such differing views demonstrate the ongoing scientific uncertainty regarding K2-18b's composition, despite promising data from the JWST.
For now, the Cambridge team remains cautiously optimistic, confident that the search for life on K2-18b will continue to evolve. "We may look back at this point in time and recognize it as the moment when the living universe came within reach," Professor Madhusudhan remarked. "This could be the tipping point in answering one of humanity's most profound questions."
As astronomers continue to study the data, the findings—while still preliminary—represent a significant step in the ongoing quest to answer one of the most fundamental questions in science: Are we alone in the universe?
The research has been published in The Astrophysical Journal Letters, and follow-up observations are planned in the coming years to further investigate the intriguing signs of life on K2-18b.