The James Webb Space Telescope (JWST), jointly developed by NASA, ESA and CSA, created the discovery on exoplanet K2-18b, located 120 light-years from Earth in the constellation Leo.
K2-18b, with 8.6 times the mass of Earth, orbits the cool dwarf star K2-18. The planet is unique among celestial bodies and belongs to the ‘Sub-Neptune’ category. But what makes this exoplanet especially interesting is that it is located in the so-called habitable zone of its star.
K2-18b could become one of the most important objects in the search for life in the universe. Research has shown that the planet may have a hydrogen-rich atmosphere and a surface covered in oceans.
The most surprising discovery, however, comes from the detection of the molecule dimethyl sulfide (DMS) in the atmosphere of K2-18b. This molecule, which is produced only by living organisms on Earth, especially marine phytoplankton, has sparked intense debate in scientific circles.
According to some researchers, the discovery of DMS on K2-18b could mean that organisms capable of producing this molecule exist on this planet.
“Our findings underline the importance of considering different habitable environments when searching for life elsewhere,” explains Nikku Madhusudhan, an astronomer at the University of Cambridge and lead author of the paper announcing these results.
“Traditionally, the search for life on exoplanets has focused mainly on smaller rocky planets, but the larger Hycean worlds are significantly more favorable for atmospheric observations.”
The abundance of methane and carbon dioxide, and the deficiency of ammonia, support the hypothesis that K2-18 b may also harbor a water ocean under a hydrogen-rich atmosphere.
These first Webb observations also allowed for a possible detection of a molecule called dimethyl sulfide (DMS). On Earth this is only produced by life. Most of the DMS in Earth’s atmosphere is emitted by phytoplankton in marine environments.
