A team of astronomers including McGill Professor Nicolas Cowan has unravelled the enigmatic atmosphere of the exoplanet HAT-P-18 b, shedding light on its intriguing blend of gases, clouds, and even the effects of its star’s activity Exoplanets, planets located beyond our Solar System, captivate both scientists and the public, holding the promise of unveiling diverse planetary systems and potentially habitable worlds. Despite being very much not like our Earth, large gas giant planets found very close to their stars have proven to be ideal test targets for telescopes like the James Webb Space Telescope (JWST) to refine astronomers’ methods of understanding exoplanets. One such planet is HAT-P-18 b, a "hot Saturn" type planet located over 500 light-years away with a mass similar to Saturn’s but a size closer to that of the larger Jupiter. This gives the exoplanet a puffed-up atmosphere that is especially ideal for analysis. Led by researchers from the Trottier Institute f