In a potential game-changer for the search for extraterrestrial life, astronomers using NASA’s James Webb Space Telescope have identified what may be the most compelling evidence yet of biology beyond Earth.
Their focus? A far-off exoplanet named K2-18 b, located 124 light-years away in the constellation Leo. Scientists detected atmospheric traces of dimethyl sulfide (DMS) and dimethyl disulfide (DMDS)—gases which, on Earth, are produced solely by living organisms, mostly marine microorganisms like phytoplankton.
The discovery, led by astrophysicist Nikku Madhusudhan of the University of Cambridge’s Institute of Astronomy, has stirred quiet excitement across the scientific community. “This marks a transformative point in our search for life beyond the solar system,” Madhusudhan explained. “We’ve shown that it’s now possible to detect biosignatures on potentially habitable planets using current technology. Welcome to the era of observational astrobiology.”
A ‘Hycean’ World in the Sweet Spot
K2-18 b is what scientists call a hycean planet—a type of exoplanet theorized to have a hydrogen-rich atmosphere and deep global oceans, offering conditions that might be suitable for microbial life. The planet is about 8.6 times more massive than Earth and orbits within the so-called habitable zone of a red dwarf star—just the right distance where liquid water could exist.
Previous observations using the Webb telescope had already confirmed the presence of methane and carbon dioxide in K2-18 b’s atmosphere. The new findings now suggest the presence of DMS or DMDS in surprisingly high concentrations—more than 10 parts per million, thousands of times higher than on Earth.
Madhusudhan cautions against leaping to conclusions: “Based on what we currently know, such concentrations cannot be explained without biological activity. However, we must repeat the observations multiple times to confirm the robustness of this signal.”
A Careful Approach to Cosmic Claims
The findings were made using the transit method, where Webb observed light from the planet’s host star filtering through its atmosphere during orbit. By analyzing how different wavelengths of light are absorbed, scientists can deduce the planet’s chemical composition.
Interestingly, DMS was initially hinted at in earlier Webb data, but this latest analysis used a different instrument and light spectrum to verify the clue.
While the possibility of alien microbes stirring in some distant ocean is thrilling, researchers remain cautiously skeptical. “These observations are an exciting step forward,” said Christopher Glein of the Southwest Research Institute, “but we need to rigorously vet the data before making any bold claims.”
In short: it’s not time to break out the welcome banner for aliens just yet—but this discovery is a massive leap forward in answering one of humanity’s oldest and most profound questions.
