First 3D view of an exoplanet's atmosphere reveals alien weather that's "Out of science fiction"

A recent study has unveiled how chemical elements and powerful winds shape the atmosphere of a planet far beyond our solar system. 

By examining separate layers of the planet’s atmosphere in 3D, the researchers have revealed an intricate system of jet streams and temperature contrasts.

The discovery was made by astronomers at the European Southern Observatory (ESO) in Chile and other institutions, who combined multiple telescope units to obtain a detailed view. 

Weather conditions on a distant world

The research focused on WASP-121b (also called Tylos), a so-called “ultra-hot Jupiter” about 900 light-years away in the constellation Puppis. The results offer an unprecedented glimpse into the weather conditions of a distant world. 

“This planet’s atmosphere behaves in ways that challenge our understanding of how weather works – not just on Earth, but on all planets. It feels like something out of science fiction,” said Julia Victoria Seidel, a researcher at the European Southern Observatory (ESO) in Chile and lead author of the study.

WASP-121b completes an orbit around its host star in roughly 30 hours, hugging it so closely that one side is perpetually scorched while the opposite side remains significantly cooler.

This extreme temperature difference results in what scientists describe as a violent and highly unusual climate. 

Distinct layers of the exoplanet’s atmosphere 

The research team used high-resolution observations of starlight passing through the exoplanet’s atmosphere to deduce how distinct layers move and mix.

“What we found was surprising: a jet stream rotates material around the planet’s equator, while a separate flow at lower levels of the atmosphere moves gas from the hot side to the cooler side. This kind of climate has never been seen before on any planet,” Seidel explained. 

By tracing iron and other gases at different heights, the scientists identified powerful winds racing across Tylos’s skies. “Even the strongest hurricanes in the Solar System seem calm in comparison,” she added.

Viewing the planet in 3D

To map out these winds and their distribution of elements, the astronomers made use of the Very Large Telescope (VLT), merging the light from four of its units into a single signal via a specialized instrument. 

The goal was to capture enough detail to distinguish chemical signatures at various altitudes – all within a single transit of WASP-121b in front of its host star.

“The VLT enabled us to probe three different layers of the exoplanet’s atmosphere in one fell swoop,” said study co-author Leonardo A. dos Santos, an assistant astronomer at the Space Telescope Science Institute in Baltimore, United States. 

By monitoring how iron, sodium, and hydrogen moved within these layers, the team reconstructed the flow of material from the planet’s deep interior to its outermost atmospheric regions. 

“It’s the kind of observation that is very challenging to do with space telescopes, highlighting the importance of ground-based observations of exoplanets,” noted dos Santos.

Metals and other compounds

The deeper parts of WASP-121b’s atmosphere feature intense heat, while the upper layers experience a dynamic interplay between cooler regions and strong winds. 

The combined data indicate that metals and other compounds are shuttled around by swift jets, leading to the unfamiliar climate patterns seen on Tylos.

Alongside iron, sodium, and hydrogen, the researchers uncovered titanium in levels just beneath the high-altitude jet stream – an unexpected finding, given that previous attempts to locate titanium in WASP-121b’s atmosphere had come up short. 

“It’s truly mind-blowing that we’re able to study details like the chemical makeup and weather patterns of a planet at such a vast distance,” said Bibiana Prinoth, a PhD student at Lund University, Sweden, and ESO.

Prinoth led a companion study published in the journal Astronomy & Astrophysics and co-authored the Nature paper.

The newly detected titanium, hidden at lower altitudes, indicates the planet’s atmosphere is even more complex than once thought. 

While it remains unclear exactly how these metals form and move around Tylos, one possibility is that temperature gradients and the planet’s day-night contrast help determine where certain elements accumulate.

Future insights on alien climates

The fact that WASP-121b’s jets and temperature distributions can be traced in such detail from light-years away marks a significant leap in exoplanet science. 

Yet, as astronomers look to study smaller, rockier planets with potentially milder climates, even more powerful instruments will be required. 

“The ELT will be a game-changer for studying exoplanet atmospheres,” Prinoth said, referring to the Extremely Large Telescope currently under construction in Chile’s Atacama Desert. 

“This experience makes me feel like we’re on the verge of uncovering incredible things we can only dream about now.”

Probing the atmospheres of exoplanets

Using next-generation telescopes such as the ELT, researchers hope to probe the atmospheres of Earth-like planets and see if they harbor any hints of habitability. 

By refining techniques already showcased in this study, astronomers aim to decode the layers, winds, and potentially life-supporting chemistry of still more distant worlds. 

The success of this recent work on WASP-121b foreshadows a new era in which entire atmospheric systems – weather, chemical cycles, and beyond – can be revealed in detail, unveiling the dynamic nature of far-off environments that were once the stuff of pure speculation.

The study is published in the journal Nature.

Image Credit: ESO/M. Kornmesser

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