WASP-17b’s Uneven Atmosphere Revealed by JWST
The James Webb Space Telescope used a new technique to map how heat and winds shape the giant planet’s day‑to‑night atmosphere.
20 Oct 2026 0 reads Compiled with AI
#WASP-17b #James Webb Space Telescope
Astronomers have used the James Webb Space Telescope to map the uneven shape of the atmosphere of the hot Jupiter WASP‑17b, a planet that orbits close to its star about 1,300 light‑years from Earth. The new technique, called transmission strings, lets scientists measure how the planet’s atmosphere looks at different points along its limb as the planet moves in front of its star. This work was led by Cornell University and the University of Bristol and was published in Nature Astronomy.
Uneven Heat Distribution
The mapping shows that the planet’s evening side, which faces the star for most of the day, is hotter and more extended than the morning side that faces away. Winds that blow from the day side to the night side carry heat and inflate the atmosphere on the evening side, creating a bulge that matches predictions from atmospheric models. The morning side contracts, giving the planet an overall oval shape.
Transmission strings differ from older eclipse‑mapping methods by studying the light that passes through each part of the planet’s limb, rather than averaging all light into a single spectrum. By pulling different distances from the planet’s center to its edge, scientists can now see latitude‑dependent temperature and chemical variations. The study confirmed that the planet’s atmosphere is a true three‑dimensional object.
These results give the first comprehensive 3‑D view of an exoplanet’s atmosphere and set a benchmark for the more than 6,000 other confirmed planets. Researchers plan to apply the technique to other worlds, which could eventually allow mapping of weather‑scale patterns on distant planets. The work demonstrates that the dynamics predicted by theory are happening, opening a new window on alien climates.