Located 124 light-years from Earth in the constellation Leo, K2-18 b orbits a red dwarf star called K2-18 (also known as EPIC 201912552).12 This exoplanet has physical characteristics that make it particularly interesting for astrobiological exploration:

• Mass: 8.6 times Earth's mass3

• Orbital period: 32.94 days4

• Orbital distance: 0.1429 AU (about 16% of Earth's distance from the Sun)5

• Classification: Sub-Neptune or mini-Neptune (between Earth and Neptune in size)

• Atmosphere: Hydrogen-rich with evidence of water vapor6

• Temperature: Approximately -8°C (265K)

Despite orbiting much closer to its star than Earth does to the Sun, K2-18 b receives similar stellar energy because K2-18 is a much cooler star than our Sun.3 The planet resides within its star's habitable zone, where liquid water could potentially exist on the surface.7 Recent observations suggest K2-18 b may be a "Hycean" world - featuring a hydrogen-rich atmosphere covering a water ocean surface - making it a prime candidate in our search for extraterrestrial life.6

In 2023, researchers using JWST's instruments detected a tentative signal of dimethyl sulfide (DMS) in K2-18 b's atmosphere, a molecule predominantly produced by marine microbes on Earth.1 By 2025, follow-up observations reportedly detected stronger signals for both DMS and dimethyl disulfide (DMDS), with researchers claiming these findings had a three-sigma level of statistical significance (0.3% probability of being due to chance).1

The scientific community remains cautious about these potential biosignatures. Some researchers argue the DMS signal strongly overlaps with methane, making it difficult to distinguish with current instruments.2 Others suggest that organisms on K2-18 b would need to produce 20 times more DMS than Earth's organisms to reach detectable levels. The Webb telescope will use more specialized instruments later in 2025 to definitively determine whether DMS exists on K2-18 b.3

Artificial intelligence is revolutionizing the search for habitable exoplanets and potential extraterrestrial life. A 2025 AI model from the University of Bern has identified 44 planetary systems likely to host Earth-like planets with a claimed 99% accuracy rate, helping astronomers prioritize targets for detailed observation.12 Machine learning algorithms are enhancing our ability to analyze the massive datasets generated by telescopes like JWST, filtering out noise and identifying subtle spectral signatures that might be missed by conventional analysis.

The Carnegie Institution for Science developed an AI model in 2023 that achieved 90% accuracy in detecting traces of extraterrestrial life by analyzing chemical distributions unique to biological processes.3 These AI systems can help determine whether detected compounds like DMS truly indicate biological activity or have alternative explanations. Advanced anomaly-detection frameworks, including autoencoders and clustering algorithms, are also being deployed to identify unusual patterns that might represent biosignatures different from those familiar to us on Earth.456

Confirming the presence of life on K2-18 b will require several additional steps beyond initial detections. The MIRI instrument on JWST, which conducted observations in April 2024, offers better capabilities for detecting DMS than instruments used in initial studies, with data still being analyzed12. Scientists emphasize that measuring potential life on another planet is "insanely difficult" and requires substantial justification, with some researchers advocating for caution until observations can be corroborated by multiple teams and non-biological hypotheses eliminated3.

To validate potential biosignatures, researchers must conduct laboratory studies investigating whether compounds like DMS can form through non-biological processes, ensure cross-validation by independent research teams using different analytical methods, and thoroughly evaluate alternative explanations for detected signals. The scientific community remains divided, with some claiming to be "99.7% sure" about findings while others maintain that stronger evidence is necessary before confirming the existence of extraterrestrial life on this intriguing exoplanet43.