The so-called Hycean planet K2–18 b is around twice the size of Earth and orbits in the habitable zone of a star located 120 light-years from our solar system. An illustration of the exoplanet K2–18 b, which dwells in the habitable zone of its star and is now known to have carbon-based molecules in its atmosphere. (Image credit: NASA, ESA, CSA, Joseph Olmsted (STScI))