Exploring a Hot Jupiter’s Atmosphere

Tidally locked hot Jupiter WASP-121b has an atmosphere so hot on one side that it breaks down water molecules and rains rubies and sapphires.

IMAGE: 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. CREDIT: Patricia Klein and MPIA

Once you find a planet, you want to learn everything you can about it, and of late, that task has expanded beyond calculating mass and density and turned to understanding distant atmospheres. We’ve talked before about how, while waiting for a certain new telescope to launch and begin actual scientific data collection, researchers have used existing telescopes to peer into exoplanetary clouds. And they’ve done some incredible work with what they had, including getting the most detailed look at the nightside of a tidally locked hot Jupiter.

The planet is WASP-121b. It was discovered in 2015, is about 855 light-years away from our solar system, and has a mass about 20% greater than Jupiter’s mass. It’s also nearly twice as big as Jupiter. Additionally, it’s tidally locked to its star, so the same side always faces the star, and it whips around in a blistering 30-hour orbit. But because we can still get some separation between the planet and the star as it orbits, we can get a glimpse of the dayside before it passes behind.

Now in a new paper published in Nature Astronomy, the researchers published the…