Webb Telescope detects compelling signatures of life in alien atmosphere

The key molecules detected are dimethyl sulphide (DMS) and dimethyl disulphide (DMDS). On Earth, these compounds are primarily byproducts of microbial life, particularly marine phytoplankton. The presence of these gases in the atmosphere of K2-18 b strongly suggests the tantalizing possibility that this distant world, located approximately 124 light-years away in the constellation Leo, could be teeming with similar microbial ecosystems.  

While the researchers, whose findings are detailed in the Astrophysical Journal Letters, are careful to emphasize that they have not definitively discovered extraterrestrial life, they express profound excitement over what they describe as a highly compelling biosignature – a chemical fingerprint indicative of biological processes. They underscore the need for further observations and rigorous analysis to confirm these initial findings.

“This is a transformational moment in the search for life beyond the solar system,” declared astrophysicist Nikku Madhusudhan of the University of Cambridge’s Institute of Astronomy, the lead author of the groundbreaking study. “We have demonstrated that it is possible to detect biosignatures in potentially habitable planets with current facilities. We have entered the era of observational astrobiology.”  

Madhusudhan noted the ongoing search for life within our own solar system, but this discovery marks a significant leap into the realm of exoplanet exploration. K2-18 b, a sub-Neptune class planet significantly larger than Earth, orbits within the habitable zone of a red dwarf star, a region where liquid water – a crucial ingredient for life as we know it – can exist on the planetary surface.  

Previous Webb observations of K2-18 b had already revealed the presence of methane and carbon dioxide, the first detection of carbon-based molecules in the atmosphere of an exoplanet within a habitable zone. The latest findings, however, provide a more direct and specific link to potential biological activity.  

“The only scenario that currently explains all the data obtained so far from JWST, including the past and present observations, is one where K2-18 b is a hycean world teeming with life,” Madhusudhan explained, referring to a class of exoplanets hypothesized to be covered in liquid water oceans with hydrogen-rich atmospheres, potentially ideal for microbial life. “However, we need to be open and continue exploring other scenarios.”  

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The detected concentrations of DMS and DMDS in K2-18 b’s atmosphere are remarkably high – thousands of times greater than their levels in Earth’s atmosphere, a fact that, according to the researchers, is difficult to explain through non-biological processes based on current scientific understanding.  

Scientists not directly involved in the study have echoed the excitement while also emphasizing the need for thorough verification. Christopher Glein of the Southwest Research Institute acknowledged the richness of the K2-18 b data but stressed the importance of rigorous testing and independent analysis.  

Madhusudhan emphasized that the next steps involve repeated observations with the Webb telescope to solidify the signal and increase the statistical significance of the detection. Additionally, further theoretical and experimental work is crucial to definitively rule out any non-biological mechanisms that could potentially produce DMS and DMDS in the specific atmospheric conditions of K2-18 b.

While acknowledging the profound implications of a potential life detection, Madhusudhan cautioned against premature claims. The current findings represent a significant stride forward in the search for life beyond Earth, offering the most compelling evidence yet that we may not be alone in the vast expanse of the universe. The coming months and years of further investigation promise to be a pivotal chapter in the field of astrobiology.