Life is Detected on a Distant Planet by Astronomers

The habitability or possibly habitation of K2-18b, a planet circling a star some 120 light-years away, requires more investigation. While the quest for extraterrestrial life has taken scientists from Martian methane to Venusian phosphine, Earth remains the only confirmed home to living organisms. However, a new study offers what researchers say could be the strongest indication yet of life beyond our planet, this time on the massive exoplanet K2-18b.

The planet’s atmosphere appears to contain dimethyl sulfide-a molecule that, on Earth, is only produced by living organisms like marine algae. Lead researcher Nikku Madhusudhan of the University of Cambridge emphasized caution, noting that while the findings are promising, declaring life would be premature. Still, he called it a revolutionary moment, describing it as the first potential biosignature spotted on a habitable exoplanet. An article in the Astrophysical Journal Letters reported the results.

Discovered in 2017 by Canadian astronomers, K2-18b belongs to a class of planets called sub-Neptunes, which are larger than Earth but smaller than Neptune. In 2021, Madhusudhan and his team proposed that some of these planets could be “Hycean”-worlds covered in warm oceans and surrounded by hydrogen-rich atmospheres.

Thanks to the James Webb Space Telescope, launched in 2021, scientists were able to analyze the atmospheric composition of such exoplanets by observing the way starlight changes as it passes through their atmospheres. In their latest observations, Madhusudhan’s team detected not just methane and hydrogen, but also dimethyl sulfide-and even its chemical cousin, dimethyl disulfide.

These signals persisted across different observations, suggesting a substantial amount of dimethyl sulfide in the planet’s atmosphere-far more than what exists on Earth. Still, some scientists caution that more data is needed. Other researchers have theorized that K2-18b might be a rocky planet with a superheated hydrogen atmosphere, not ideal for life.

Lab experiments and additional telescope observations will be necessary to better understand how dimethyl sulfide behaves under different planetary conditions. Scientists are eager to see what further investigations by the Webb telescope might reveal. New, more advanced telescopes are also in development to deepen the search for life beyond Earth.

While researchers remain cautious about making definitive claims, the discovery has stirred significant excitement. As one scientist humorously noted, “I’m not screaming ‘aliens!’-but I reserve the right to.”