Exoplanet weather report: hot with a chance of cyclone

Astronomers have found a world less than 900 light-years away in space being whipped and battered by enormous cyclones.

The findings, which relied on previous Hubble Space Telescope observations, show brutal storms are repeatedly created and destroyed in the vast temperature swings between the side of the exoplanet that faces its host star and the side in darkness.

WASP-121b, sometimes known as Tylos, the ancient Greek name for Bahrain, hugs its star so tightly that its upper atmosphere is 3,400 degrees Fahrenheit – twice as hot as the typical cremation oven. (We looked it up.)

To help visualize this hellscape, a team of scientists supported by NASA and the European Space Agency created a video, below, that shows the exoplanet's weather in action. And if you think those undulations look punishing, consider this: The whole thing has been slowed down to allow people to see the weather patterns in closer detail.

Credit: NASA / ESA / Quentin Changeat (ESA / STScI) / Mahdi Zamani (ESA / Hubble)

Needless to say, Tylos isn't one of those exoplanets scientists are thinking could be a Plan B for Earth. But as experts learn how to study weather on exoplanets, this research could help them find the worlds with more temperate climates in the future.

To make the discovery, the international team assembled and reprocessed Hubble archives from 2016, 2018, and 2019. The researchers used the data to infer the chemistry, temperature, and clouds of the atmosphere at different times, said Quentin Changeat, co-author on the paper accepted for publication in The Astrophysical Journal Supplement. Then, the team used computer simulations to model the drastic weather variations.

"This provided us with an exquisite picture of the planet changing over time," he said in a statement.

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The number of confirmed exoplanets — planets orbiting stars other than the sun — has risen to 5,566, with over 10,000 more candidates under review.

The growing tally only scratches the surface of planets believed to be in the cosmos. With hundreds of billions of galaxies, the universe likely teems with many trillions of stars. And if most stars have one or more planets around them, that's an unfathomable number of worlds.

Tylos is a type of exoplanet known as an ultra-hot Jupiter, a world more massive than the actual Jupiter that orbits extremely close to its star. The giant exoplanet orbits its star in under 1.5 Earth days.

It's a strange place that gets stranger with every study. In 2022, scientists suspected the world's dark side is cool enough to host metal clouds that rain liquid gems.

A "torrent" of ultraviolet light from the host star is heating the planet's upper atmosphere, causing magnesium and iron to vaporize and vent into space as gas, according to the Space Telescope Science Institute in Baltimore.

And the gravitational forces from the star are so strong, they seem to have smushed the planet into a football shape.