Astronomers have long depicted distant exoplanets with smooth, circular outlines. But new observations reveal that the atmospheres surrounding some of these scorching alien worlds can have surprisingly uneven shapes. Using NASA's James Webb Space Telescope (JWST), researchers have discovered that the atmosphere of WASP-17b, a giant planet roughly 1,300 light-years from Earth, extends farther outward on one side than the other.
Although its overall outline remains approximately circular, its atmosphere is noticeably asymmetrical. The distortion provides new evidence of how extreme temperatures and powerful winds reshape the atmospheres of distant planets. The discovery, published in Nature Astronomy, comes from a study jointly led by Cornell University in the United States and the University of Bristol in the United Kingdom.
Researchers used an innovative technique called 'transmission strings', developed by Bristol astrophysicists Dr. Hannah Wakeford, to investigate the planet's atmospheric structure in unprecedented detail. James Webb Reveals the 3D Structure of an Alien Atmosphere WASP-17b belongs to a class of planets known as 'hot Jupiters', enormous gas giants that orbit close to their host stars and experience intense heating.
Its unusual atmospheric shape offers a new perspective on how heat moves around these extreme worlds. Lili Alderson, a Klarman Postdoctoral Fellow at Cornell University, began the research while studying at the University of Bristol, where she earned her doctorate in physics. "This is proof of concept that planets are in fact 3D objects, and that consistently, as they go around their star, what we predict should be happening is happening.
To move beyond computational exercises and see it for real is a different matter." The observations provide valuable information about WASP-17b's atmospheric chemistry and temperature variations, including differences between its equator and poles and between its permanently illuminated and dark hemispheres. These results closely match earlier theoretical predictions and computer models. Together, they offer one of the most detailed three-dimensional pictures of an exoplanet's atmosphere yet produced, establishing a useful reference point for studying the more than 6,000 exoplanets confirmed so far.
Hannah Wakeford, Associate Professor in Astrophysics at the University of Bristol, said: "Planets are temperamental, their atmospheres complex and chaotic. The fact that all of these numbers came together and showed us this very structured, dynamical picture of this giant world over 1,000 light-years away was just really exciting." A New Technique Uncovers Hidden Atmospheric Features James Webb's extraordinary sensitivity has already enabled scientists to investigate alien atmospheres using a method called eclipse mapping. This approach examines subtle changes in light as a planet moves behind its parent star, helping researchers determine how conditions vary across the planet.
Extract — continue reading at the source.
