James Webb Space Telescope Detects Biosignature Candidate

NASA's James Webb Space Telescope reported tentative spectroscopic evidence of dimethyl sulfide — a molecule on Earth produced exclusively by living organisms — in the atmosphere of exoplanet K2-18b in 2025. While scientists cautioned that abiotic production pathways could not be ruled out, the finding was described as the most significant potential biosignature detection in the history of astronomy. Follow-up observations were scheduled for 2026 to confirm or refute the signal.