Could this exoplanet be 'full of life'? Clues of life beyond our solar system.

      Illustration of a Hycean world.

      A. Smith, N. Madhusudhan (University of Cambridge)

      In a remarkable new discovery, astronomers have found what they assert is the strongest evidence to date of life beyond our solar system. Utilizing the James Webb Space Telescope, researchers from the University of Cambridge, UK, have identified a compound on the planet K2-18b that is produced by microbial life.

      The study indicates that K2-18b is likely a Hycean planet, situated within its star's habitable zone and covered by a liquid water ocean. This type of planet is considered an ideal candidate for the search for life due to its abundant water and hydrogen-rich atmosphere.

      When researchers examined the planet using Webb’s Mid-Infrared Instrument (MIRI), they discovered the chemical signature of dimethyl sulfide (DMS) and/or dimethyl disulfide (DMDS). On Earth, these compounds are exclusively produced by life forms like marine phytoplankton, and while they exist in minuscule amounts here, they are present on K2-18b in quantities thousands of times greater.

      “Previous theoretical studies suggested that high levels of sulfur-based gases like DMS and DMDS could be found on Hycean worlds,” stated lead researcher Nikku Madhusudhan. “Now we've observed it, confirming earlier predictions. Based on what we know about this planet, a Hycean world with an ocean rich in life fits the data best.”

      Despite this, the researchers caution that this does not constitute definitive proof of life, as the compound could potentially be generated by an unknown chemical process. Additionally, prior studies on K2-18b did not find evidence of DMS or DMDS, and detecting compounds in the atmosphere of such a faraway planet presents challenges, making the findings contentious.

      “It’s crucial to maintain a healthy skepticism about our findings, as it’s through rigorous testing that we can gain confidence in them,” Madhusudhan remarked. “That’s the essence of scientific inquiry.”

      The team aims to conduct further studies to determine whether DMS and DMDS could arise from chemical reactions instead of biological processes, particularly given the large quantities identified on the planet. They view their results as a "starting point" for additional exploration in the quest for extraterrestrial life.

      “Years from now, we may reflect on this moment as when the living universe became more accessible,” Madhusudhan suggested. “This could mark a pivotal moment where the fundamental question of our solitude in the universe becomes one we can begin to answer.”

      The research has been published in The Astrophysical Journal Letters.

      Georgina has been writing about space for Digital Trends for six years, covering topics related to human space exploration and planetary science.

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