Scientists Unveil 3D Structure of Exoplanet WASP-121b for the First Time
Astronomers have, for the first time, mapped the three-dimensional structure of an exoplanet’s atmosphere, uncovering three distinct layers on a scorching-hot gas giant called WASP-121b, also known as Tylos. This breakthrough offers new insights into atmospheric behaviour beyond our solar system.
WASP-121b: A Wedding Cake-Like Atmosphere
Using the European Southern Observatory’s Very Large Telescope in Chile, researchers detected a layered atmosphere on WASP-121b, which orbits a star larger and hotter than the Sun. Until now, scientists could identify chemical elements in exoplanet atmospheres but had never mapped their vertical distribution.
WASP-121b belongs to a class of exoplanets known as “ultra-hot Jupiters”—gas giants that orbit extremely close to their stars, reaching extreme temperatures. Its atmosphere primarily consists of hydrogen and helium, similar to Jupiter, but behaves in an entirely unique way.
The three atmospheric layers were identified based on their chemical composition:
- Bottom Layer: Rich in gaseous iron due to the planet’s extreme heat, with winds transporting gas from the permanently hot side to the cooler side.
- Middle Layer: Dominated by sodium, with a jet stream circling the planet at an incredible 70,000 km/h (43,500 mph)—faster than any winds in our solar system.
- Upper Layer: Primarily hydrogen, with some escaping into space.
Titanium in gaseous form was also detected, a stark contrast to Earth, where iron and titanium remain solid due to much lower temperatures.
A Record-Breaking Exoplanet
WASP-121b is roughly the same mass as Jupiter but twice its diameter, making it significantly puffier. Located about 900 light-years away in the constellation Puppis, the planet is tidally locked—one side permanently faces its star while the other remains in darkness.
Its day side reaches a staggering 4,900°F (2,700°C), while the night side remains at around 2,200°F (1,250°C). The planet orbits its star at just 2.5% of Earth’s distance from the Sun, completing a full orbit in only 1.3 days. Its host star, WASP-121, is 1.5 times the mass and diameter of the Sun and significantly hotter.
A Step Towards Finding Habitable Worlds
The ability to study an exoplanet’s atmospheric structure is a major milestone in the search for potentially habitable planets. Lead researcher Julia Victoria Seidel from the European Southern Observatory stated that this discovery challenges existing theories of planetary climates.
“In the future, we will likely be able to provide similar observations for smaller and cooler planets, making them more comparable to Earth,” said co-author Bibiana Prinoth from Lund University in Sweden. The upcoming Extremely Large Telescope in Chile, set to be the world’s largest optical telescope, could further these studies.
This research not only expands our understanding of exoplanets but also provides a broader perspective on Earth’s uniqueness in the universe.
With inputs from Reuters
