Mark Megahan
If you grab your towel, stick out your electronic thumb, and manage to hitch a lift to exoplanet WASP-121b, only 855 light-years from Earth, you’ll find some really freaky weather. Bring a big bucket because the forecast might call for raining rubies or snowing sapphires.
Jupiter like ultra-hot exoplanet
The exoplanet which Terran astronomers like to call WASP-121b has some really fierce weather. Hurricanes here are calm and sunny days compared to what meteorological conditions are like there.
One of the reasons is truly intense heat. Imagine a gas giant planet like Jupiter as close to it’s host star as Mercury.
Just like the Moon is tidal locked to Earth, keeping the same face to us all the time, WASP-121b has one side always facing it’s parent star.
The exoplanet has water, just not in a form you would actually recognize, and it constantly cycles between the day and night side. First discovered in 2015, they measured it as larger than Jupiter and hotter than Mercury. The more they learn, the stranger it gets.
That water for instance. Instead of Nitrogen and Oxygen for an atmosphere as we have here on earth, with water laying safely in the oceans, water on the strange and fierce exoplanet forms the air, and it’s colorful, too.
The alien world “has a glowing water vapor atmosphere and is being deformed into the shape of a football due to the intense gravitational pull of the star it orbits.” That orbit is a really close one. A one orbit year there happens every 30 hours, while the day is infinite.
A different beast
Astronomers are familiar with hot Jupiter like planets and say they’re “famous for having very bright day sides, but the night side is a different beast.” WASP-121b’s night side is one to scare werewolves.
Because it’s “10 times fainter than its day side,” things get really interesting. Tansu Daylan at Massachusetts Institute of Technology has a few things to say about the weather on the exoplanet. He studied both the night and day sides extensively.
Here on Earth, water evaporates into the air and water vapor condenses into clouds which release rain. On exoplanet WASP-121b, fragile water molecules are ripped to their composite quarks by the blazing hot temperatures experienced by the planet on the day side.
The 11,000 miles per hour wind blows them around to the night side and they turn back into water for a while before doing it again in the morning. Meanwhile, molecules of metal get the same treatment, but they are able to condense and form metallic clouds of “iron and corundum” Corundum, the experts note, “is a mineral found in rubies and sapphires.”
As the metal clouds are blown to the day side they instantly vaporize. Right at the boundary line, the clouds release their rain of liquid gems. Astronomers can’t wait to get a good glimpse of this exoplanet with the James Webb Space Telescope. Projects like this are exactly why they built it.
“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,” notes study coauthor Joanna Barstow.
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