Free Astronomy Magazine March-April 2024

27 MARCH-APRIL 2024 spectral signature (which signifies the chemical composition of the ex- oplanet’s atmosphere) indicative of a changing atmosphere. Next, the team used highly sophisticated com- putational models to attempt to un- derstand observed behaviour of the exoplanet’s atmosphere. The models indicated that their results could be explained by quasi-periodic weather patterns, specifically massive cy- clones that are repeatedly created and destroyed as a result of the huge temperature difference be- tween the star-facing and dark side of the exoplanet. This result represents a significant step forward in potentially observ- ing weather patterns on exoplanets. “The high resolution of our exo- planet atmosphere simulations al- lows us to accurately model the weather on ultra-hot planets like WASP-121 b,” explained Jack Skin- ner, a postdoctoral fellow at the Cal- ifornia Institute of Technology and co-leader of this study. “Here we make a significant step forward by combining observational constraints with atmosphere simulations to un- derstand the time-varying weather on these planets.” “Weather on Earth is responsible for many aspects of our life, and in fact the long-term stability of Earth’s climate and its weather is likely the reason why life could emerge in the first place,” added Changeat. “Studying exoplanets’ weather is vital to understanding the complexity of exoplanet atmos- pheres, especially in our search for exoplanets with habitable condi- tions.” Future observations with Hubble and other powerful telescopes, in- cluding Webb, will provide greater insight into weather patterns on distant worlds: and ultimately, pos- sibly to finding exoplanets with sta- ble long-term climates and weather patterns. ! T his is an artist’s impression of the exo- planet WASP 121-b, also known as Tylos. The exoplanet’s appearance is based on Hubble data of the object. [NASA, ESA, Q. Changeat et al., M. Zamani (ESA/Hubble)]