Scientists have uncovered new, tentative signs that life could exist on a distant planet, K2-18b, located over 700 trillion miles from Earth. A team from Cambridge University, using NASA’s James Webb Space Telescope (JWST), detected molecules in the planet’s atmosphere that are typically associated with life on Earth. Though these findings are still under review, researchers are hopeful that further data could confirm the existence of life elsewhere in the universe.
What We Know About K2-18b
K2-18b is an exoplanet orbiting a star in the constellation Leo, and it is roughly 2.5 times the size of Earth. It is located 700 trillion miles away, an almost incomprehensible distance. The planet’s atmosphere is being closely studied by scientists, and the latest findings have added a new layer of excitement to the search for extraterrestrial life.
The breakthrough comes from the James Webb Space Telescope, a cutting-edge observatory that allows astronomers to study distant worlds in unprecedented detail. JWST can analyze the chemical composition of a planet’s atmosphere by detecting light that filters through it from the star it orbits.
Key Molecules Found in the Atmosphere
The Cambridge team detected traces of two molecules—dimethyl sulphide (DMS) and dimethyl disulphide (DMDS)—in K2-18b’s atmosphere. These chemicals are known to be produced by marine phytoplankton and bacteria on Earth, suggesting that life might play a role in their presence. The discovery marks the second time these molecules have been identified on K2-18b, with previous findings raising interest but lacking enough data for definitive conclusions.
The Research Team’s Excitement and Caution
Prof Nikku Madhusudhan, the lead researcher, shared his excitement about the discovery but also stressed the need for more data to confirm the findings. He described the results as the “strongest evidence yet” for the possibility of life beyond Earth. “If we confirm this signal, it could change everything about our understanding of life in the universe,” he said.
However, the team remains cautious. For these findings to be scientifically valid, they must reach a statistical threshold called “five sigma”—a 99.99999% certainty that the results are not due to random chance. The current data stands at a 99.7% confidence level, which, while promising, is still below the necessary standard.
Scientific Debate and Alternative Theories
Despite the promising signals, many experts remain skeptical, and alternative explanations for the findings are being debated. Prof Catherine Heymans, an independent astronomer from Edinburgh University, noted that even if the data reaches the five sigma level, the presence of DMS and DMDS alone doesn’t guarantee that the gases are of biological origin.
“We know these molecules can be produced by microorganisms on Earth, but it’s possible that non-biological processes on K2-18b could explain the presence of these gases,” Prof Heymans said. “Geological processes, for example, could produce similar chemical signatures.”
The Cambridge team is working with other researchers to test whether DMS and DMDS can be produced through non-living processes in the laboratory, which would help clarify whether biological life is the source.
The Planet’s Mysterious Composition
Beyond the discovery of potential life-signature molecules, there is ongoing debate about the overall structure of K2-18b. Some scientists, including Prof Oliver Shorttle from Cambridge, believe the planet may have a vast liquid ocean beneath its atmosphere, which could support life. However, others, like Dr. Nicolas Wogan at NASA’s Ames Research Center, suggest that K2-18b may be a mini gas giant, lacking a solid surface altogether.
These differing theories highlight the challenges scientists face in interpreting data from distant exoplanets. The limited amount of light that can be captured from such faraway worlds makes it difficult to draw firm conclusions.
What’s Next in the Search for Life?
As the scientific debate continues, the next steps are clear: more data and more observations. The research team hopes to refine their findings in the coming years, with Prof Madhusudhan predicting that confirmation of life on K2-18b could come within the next one to two years.
“We’re on the right track, but it’s still early days,” he said. “The implications of this discovery are huge. If life exists on K2-18b, it would suggest that life is common throughout the galaxy.”
