The distant world WASP-121b is already bizarre. It's football-shaped and rains gems.
Now, astronomers leveraged the power of four telescopes to observe what's transpiring deep inside this giant exoplanet's swirling atmosphere. They found never-before-seen activity.
"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," Julia Victoria Seidel, a researcher at the European Southern Observatory who led the new research, said in a statement.
The research has been published in the peer-reviewed journal Nature.
WASP-121b is an exoplanet (meaning a world beyond our solar system) called a "hot Jupiter" because it's a gaseous giant that orbits close to its searing star. Crucially, the planet is tidally locked to its star — like the moon is locked to Earth — meaning that one side of WASP-121b is incessantly seared by its star, while the other is dark and cooler.
The combined light from four of the telescopes comprising the European Southern Observatory’s Very Large Telescope — located at 8,648 feet of elevation in the Chilean desert — observed WASP-121b, located some 900 light-years away in deep space (a single light-year is nearly 6 trillion miles). As the planet passed in front of its nearby star, the telescopes detected the starlight passing through WASP-121b's atmosphere, enabling the astronomers (with the help of an instrument called a spectrograph that can detect materials in far-off objects) to see different chemical elements moving through different atmospheric layers.
Because each layer in the planet's atmosphere hosts unique winds carrying different elements, the researchers could map an unprecedented 3D structure of an exoplanet's atmosphere.
As the graphic below shows, WASP-121b contains iron winds at its lowest known layer, which blow away from the point on the exoplanet where its extremely close star is located overhead. In the middle is a quickly moving jet stream of sodium, which moves faster than the planet rotates. Finally, the planet is topped with an upper layer of hydrogen winds.
"This kind of climate has never been seen before on any planet," Seidel explained.
"This kind of climate has never been seen before on any planet."
"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," added Bibiana Prinoth, an astrophysicist at Lund Observatory who coauthored the research.
Planets like Earth and Jupiter have jet streams, too, but they don't contain this onion-like layer of rapidly moving winds.
That sodium jet stream is particularly potent. It accelerates as it flows into the planet's hot dayside, roiling the atmosphere and spawning potent storms.
"Even the strongest hurricanes in the Solar System seem calm in comparison," Seidel said.
With the bigger, looming telescopes of the future, exoplanet researchers plan to peer into much smaller, rocky worlds — perhaps somewhat like Earth. The Extremely Large Telescope (ELT) — packing a 128-foot-wide mirror that will make it the world's largest visible and infrared light telescope — is under construction and slated to start operating in 2028 atop Chile's Atacama Desert.
What will we find in the clouds of more alien worlds?
