JWST Maps Lopsided Atmosphere of Hot Jupiter WASP-17b
Astronomers used the James Webb Space Telescope to map the uneven atmosphere of WASP-17b, a hot Jupiter about 1,300 light-years away, finding one side extends farther into space than the other. The pattern matches expectations for powerful equatorial winds moving heat from the permanent dayside to the nightside. The study applied a new method called transmission strings to distinguish conditions around the planet's atmospheric limb.
WASP-17b is a gas giant orbiting very near its star roughly 1,300 light-years away, so one hemisphere always faces the star while the other stays dark. The new work, published in Nature Astronomy and co-led by Cornell and Bristol, is the first use of transmission strings — also called transit mapping — a technique created at Bristol by David Grant and Hannah Wakeford.
Rather than averaging light across the whole atmospheric rim, the method tracks the planet as it crosses its star and separates conditions at different points along that edge. Lead author Lili Alderson, now at Cornell, compared the advance to moving from a plain ring to knowing where its gemstones sit.
This result may deepen public interest in exoplanet science, showing that distant worlds have weather rather than uniform hazes. Astronomers could use transmission strings on other hot Jupiters, potentially refining how atmospheres are modeled. For observatories and funding bodies, such demonstrations may strengthen the case for continued space telescope time. General audiences likely see little direct change, though the imagery and accessible framing of alien weather could shape science communication and education.