In an extraordinary breakthrough, astronomers led by the University of Cambridge have detected chemical markers in the atmosphere of exoplanet K2-18b that may hint at the presence of life.
Using the James Webb Space Telescope (JWST), researchers identified dimethyl sulfide (DMS) and/or dimethyl disulfide (DMDS)—compounds on Earth produced exclusively by microbial life, like marine phytoplankton.
Located 124 light-years away in the constellation Leo, K2-18b orbits its star in the habitable zone. At 8.6 times Earth’s mass and 2.6 times its size, the exoplanet is classified as a “Hycean” world—a planet thought to host habitable oceans beneath a hydrogen-rich atmosphere.
Detecting these potential biosignature molecules marks the most substantial evidence yet for the existence of extraterrestrial life.
DMS and DMDS were detected through JWST’s advanced spectroscopic tools, which analyze starlight passing through a planet’s atmosphere as it transits its star. Earlier observations using JWST’s near-infrared instruments hinted at the presence of DMS.
Independent observations with the telescope’s mid-infrared instrument have confirmed these findings with “strong and clear” signals.
Notably, the estimated levels of these molecules in K2-18’s atmosphere are thousands of times greater than those found on Earth, over 10 parts per million compared to Earth’s sub-part-per-billion levels.
Researchers emphasize that while this aligns with predictions for a Hycean world teeming with life, further investigation is crucial to rule out non-biological processes.
The current observations are at the “three-sigma” level of statistical significance, meaning there is a 0.3% chance that the results are random.
Additional observation time with JWST is required to achieve the accepted threshold for scientific discovery (five sigma). Between 16 and 24 hours of further study could validate these tantalizing findings.
“This discovery is remarkable, but science demands rigor. We must remain skeptical and pursue further analysis to confirm these results,” said Professor Nikku Madhusudhan, the study’s lead author from Cambridge’s Institute of Astronomy. He added that unknown chemical processes could still account for the observations, making caution essential.
The potential implications are profound. This discovery offers insights into fast radio bursts, Ocean planets, and the larger search for life in the cosmos. Researchers plan to conduct experimental and theoretical studies to explore whether DMS and DMDS could arise through non-biological processes.
“Decades from now, we may look back on this moment as the tipping point when the living universe became more than a distant dream,” Madhusudhan reflected. “This is a giant leap forward in our quest to answer the ultimate question: Are we alone?”
The James Webb Space Telescope, a collaboration between NASA, ESA, and the Canadian Space Agency, continues to revolutionize our understanding of the universe, moving humanity ever closer to unraveling its mysteries.
Journal Reference:
- Nikku Madhusudhan, Savvas Constantinou, Måns Holmberg, Subhajit Sarkar, Anjali A. A. Piette, and Julianne I. Moses. New Constraints on DMS and DMDS in the Atmosphere of K2-18 b from JWST MIRI. The Astrophysical Journal Letters, DOI 10.3847/2041-8213/adc1c8
Source: Tech Explorist
