Additional Coverage:
Could there be life beyond Earth? Scientists find compelling new clues on distant planet.
Astronomers announced exciting new hints of potential life on a planet outside our solar system, though the scientific community remains cautiously optimistic. The planet, K2-18b, located 124 light-years away in the Leo constellation, has been the subject of much debate, focusing on whether it could be an ocean world capable of supporting microbial life.
Using the James Webb Space Telescope, a joint British-U.S. research team detected dimethyl sulfide (DMS) and dimethyl disulfide in K2-18b’s atmosphere. These chemicals are considered potential “biosignatures,” meaning they could indicate the presence of life. On Earth, these chemicals are primarily produced by phytoplankton, a type of microscopic marine algae.
While the discovery is significant, researchers urge caution. More observations are needed to confirm these findings.
Lead researcher Nikku Madhusudhan, an astrophysicist at Cambridge University, expressed hope that conclusive evidence could be obtained within the next one to two years. However, other experts point to past controversies surrounding K2-18b, suggesting these chemicals might have non-biological origins.
K2-18b is unique among the approximately 6,000 exoplanets discovered so far because it orbits its star within the habitable or “Goldilocks” zone. This means the planet is neither too hot nor too cold for liquid water, a key ingredient for life as we know it. Telescopes study distant exoplanets by observing them as they pass in front of their stars, analyzing how molecules in their atmospheres block starlight.
In 2023, the Webb telescope detected methane and carbon dioxide in K2-18b’s atmosphere, marking the first time such carbon-based molecules were found on a habitable-zone exoplanet. Weaker signs of DMS were also detected, prompting further investigation.
A year ago, Webb was again pointed at K2-18b, this time using its mid-infrared instrument, revealing much stronger signs of both DMS and dimethyl disulfide. Although these signals haven’t yet reached the “five sigma” threshold of statistical significance typically required for scientific discoveries, the findings remain promising.
The presence of DMS doesn’t definitively prove life exists on K2-18b. Scientists discovered traces of DMS on a comet last year, suggesting it can be produced without life. However, the concentration of DMS on K2-18b appears to be thousands of times stronger than on Earth, possibly pointing to a biological source.
K2-18b is a prime candidate for a “hycean planet,” a type of ocean world larger than Earth with a hydrogen-rich atmosphere. Hycean planets are thought to be covered in oceans and have hydrogen-rich atmospheres, both essential for life.
Many of these planets are larger and hotter than Earth. While they might not host intelligent life, they could support microbial life similar to that found in Earth’s early oceans.
Some scientists remain skeptical, questioning whether proposed hycean planets, including K2-18b, are too close to their stars for liquid water. Further research and observations with the Webb telescope will be crucial in determining whether K2-18b harbors life or not. This discovery has the potential to revolutionize our understanding of life in the universe.