'Never before seen': Exoplanet's atmosphere mapped in 3D

"A science fiction movie." ESO astronomers have successfully mapped the atmosphere of an exoplanet 900 light-years away in 3D, revealing a "unique climate" with powerful winds carrying iron and titanium, according to a study published Tuesday (February 18).

"It feels like a science fiction film," enthuses Julia Victoria Seidel, a researcher at the European Southern Observatory (ESO) and lead author of this study published in Nature.

"The atmosphere of this planet behaves in a way that challenges our understanding of how weather works, not just on Earth, but on all planets," she explains in an ESO statement.

WASP-121b, also known as Tylos, is an ultra-hot Jupiter located in the constellation Puppis, 900 light-years from Earth. This gas giant is so close to its star that it orbits it every thirty Earth minutes.

One side is hot, because it always faces the star, while the other is much colder. This extreme contrast in temperatures poses a climate conundrum: how is the energy distributed?

By combining the four telescopes of ESO's Very Large Telescope (VLT) in Chile, astronomers were able to probe three different layers of Tylos' atmosphere at once. In particular, they were able to track the movements of iron, sodium and hydrogen, which allowed them to trace winds in the deep, middle and surface layers of the atmosphere.

The researchers discovered a complex weather system. A jet stream swirls material around the planet's equator. At lower levels of the atmosphere, a separate flow moves gas from the warm side to the cold side. The jet stream stretches across half the planet, picking up speed and violently churning the atmosphere high into the sky as it passes over the hot side of Tylos.

"Even the most violent hurricanes in the solar system seem calm by comparison," says Julia Victoria Seidel, who points out that "this type of climate has never been observed before on any planet."

The observations also revealed the presence of titanium just below the jet stream, whereas previous observations of the planet had not revealed the presence of this element, perhaps because it was hidden deep in the atmosphere.

"It is truly incredible that we can study details such as the chemical composition and weather conditions of a planet from such a great distance," said Bibiana Prinoth, a researcher at Lund University in Sweden and co-author of the study, quoted by ESO.