Wild exoplanet has metal clouds and rain of liquid gems

By Georgina Torbet February 21, 2022

In the pantheon of weird exoplanets, one of the strangest has to be WASP-121 b. It’s so close to its star that not only is its surface temperature estimated to be up to an unimaginable 4,600 degrees Fahrenheit, but gravitational forces are pulling the planet apart and shaping it like a football. Now, new research reveals what the weather might be like on this hellish planet, and it’s just as weird as you might think.

Located 855 light-years away, the planet is a type called a hot Jupiter because it’s comparable in mass to Jupiter, at 1.2 times its mass, but its diameter is nearly twice as large. One reason that the planet has such extreme conditions is that it’s close to its star that it is tidally locked, meaning one side of the planet called the dayside always faces the star and has the hottest temperature, while the cooler side called the nightside always faces away from the star into space.

Artist's impression of the exoplanet WASP-121 b. — Artist’s impression of the exoplanet WASP-121 b. It belongs to the class of hot Jupiters. Due to its proximity to the central star, the planet’s rotation is tidally locked to its orbit around it. As a result, one of WASP-121 b’s hemispheres always faces the star, heating it to temperatures of up to 3000 degrees Celsius. The night side is always oriented towards cold space, which is why it is 1500 degrees Celsius cooler there. Patricia Klein and MPIA

In this new study, researchers from the Max Planck Institute for Astronomy looked at the water cycle between the planet’s dayside and nightside. It’s always too hot there for water to form clouds, but that doesn’t mean there aren’t cloudy skies there. The researchers found the nightside has some wild weather phenomena including metal clouds. The clouds consist of metals like iron, magnesium, chromium, and vanadium, which melt into their gas form on the dayside and condense into liquid clouds on the nightside.

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And it gets weirder still. The researchers didn’t find indications of aluminum or titanium in the atmosphere, which they expected. They think these metals must have condensed and fallen as rain in lower levels of the atmosphere which they couldn’t see.

“This rain would be unlike any known in the Solar System,” the Max Planck Institute for Astronomy writes. “For instance, aluminum condenses with oxygen to form the compound corundum. With impurities of chromium, iron, titanium, or vanadium, we know it as ruby or sapphire. Liquid gems could therefore be raining on the nightside hemisphere of WASP-121 b.”

Researchers want to study this planet in more detail to learn about its strange ways, and they plan to observe it further using the recently launched James Webb Space Telescope.

“It’s exciting to study planets like WASP-121 b that are very different to those in our Solar System because they allow us to see how atmospheres behave under extreme conditions,” co-author Joanna Barstow said in a statement.

The research is published in the journal Nature Astronomy.

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Georgina Torbet

Space Writer

Georgina has been the space writer at Digital Trends space writer for six years, covering human space exploration, planetary…

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