JWST has mapped changing weather on WASP-94A b, a hot gas giant 700 light-years away. Scientists found clouds in the morning but clear skies in the evening, suggesting previous atmospheric studies might be incorrect. The tidally locked planet has a mass below half of Jupiter but is 70% wider, making its atmosphere easier to observe.

Using limb-resolved spectroscopy, researchers detected different atmospheric compositions between the planet's morning and evening limbs. The morning showed high-altitude aerosols blocking light from deeper layers, while the evening revealed water vapor. Temperature differences of up to 450 Kelvin drive equatorial winds that transport clouds from the night side.

Traditional atmospheric models gave biased results when averaging the entire planet, suggesting metallicity was 100 times higher than the sun. This finding affects how scientists study tidally locked planets, potentially requiring new methods to analyze averaged spectra and improve our understanding of exoplanet atmospheres.