JWST Maps Uneven Atmosphere on Puffy Hot Jupiter
Researchers used JWST observations and a new modeling approach to examine different regions of WASP-17b's atmosphere rather than averaging the whole planet. The work reveals a lopsided exoplanet with distinct atmospheric conditions, including powerful evening winds.
WASP-17b, found in 2009 about 1,300 light-years away in Scorpius, is an extreme hot Jupiter: it completes an orbit in four days, has roughly half Jupiter’s mass, and is inflated to almost twice Jupiter’s width, giving it foam-like density. Its large, hot atmosphere makes it a testbed for exoplanet climate studies.
Instead of averaging the whole silhouette, the team used “transmission strings” and Harmonica modeling to compare light passing through different edges during transit. JWST’s infrared resolution showed a tidally locked world with a 650 K spread between morning and evening edges and an evening atmosphere 1.8 times larger, consistent with eastward equatorial jet streams.
This result may mainly affect exoplanet researchers, who could use edge-by-edge JWST observations to test atmospheric models more precisely, and instrument or software teams whose methods may be adapted for other worlds. It could also shape science communication and education by giving the public a clearer picture of alien weather, while potentially influencing how future telescope time is prioritized for detailed atmospheric mapping. These are plausible benefits, not guaranteed outcomes.