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One of the principal investigators of the team, Quentin Changeat, an ESA Research Fellow at the Space Telescope Science Institute, elaborates:
“Our dataset represents a significant amount of observing time for a single planet and is currently the only consistent set of such repeated observations. The information that we extracted from those observations was used to characterise (infer the chemistry, temperature, and clouds) of the atmosphere of WASP-121 b at different times. This provided us with an exquisite picture of the planet, changing in time.”
After cleaning each dataset, the team found clear evidence that the observations of WASP-121 b were varying in time. While instrumental effects could remain, the data showed an apparent shift in the exoplanet’s hot spot [5] and differences in spectral signature (which signifies the chemical composition of the exoplanet’s atmosphere) indicative of a changing atmosphere. Next, the team used highly sophisticated computational models to attempt to understand observed behaviour of the exoplanet’s atmosphere. The models indicated that their results could be explained by quasi-periodic weather patterns, specifically massive cyclones that are repeatedly created and destroyed as a result of the huge temperature difference between the star-facing and dark side of the exoplanet. This result represents a significant step forward in potentially observing weather patterns on exoplanets.
“The high resolution of our exoplanet atmosphere simulations allows us to accurately model the weather on ultra-hot planets like WASP-121 b,” explained Jack Skinner, a postdoctoral fellow at the California Institute of Technology and co-leader of this study. “Here we make a significant step forward by combining observational constraints with atmosphere simulations to understand 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 Quentin. “Studying exoplanets’ weather is vital to understanding the complexity of exoplanet atmospheres, especially in our search for exoplanets with habitable conditions.”
Future observations with Hubble and other powerful telescopes, including Webb, will provide greater insight into weather patterns on distant worlds: and ultimately, possibly to finding exoplanets with stable long-term climates and weather patterns.