A spectroscopic map of Ultra-Hot Jupiter WASP-121b using JWST (Astronomy Theory)

WASP-121b is a type of exoplanet - a planet that is outside of our Solar System - called an "ultra-hot Jupiter" because it is a gas giant, like Jupiter, but it is much closer to its star and therefore much hotter. In fact, the temperature in the day on WASP-121b is estimated to be over 2500 degrees C!

But the nights ould much colder...

WASP-121b always shows the same face to its star, pretty much like the Moon around our own planet, and it means that one side of WASP-121b is always in hot and bright while the other side is always in cold and dark.

WASP-121b is the first exoplanet found to contain water H2O in an extrasolar planetary stratosphere (i.e., an atmospheric layer in which temperatures increase as the altitude increases) but it also contains a lot of exotic chemical species, such as vanadium oxide VO, silicon monoxide SiO, vanadium V, iron Fe, magnesium Mg, and calcium Ca.

WASP-121b has recently been observed by the brand-new James Webb Space Telescope in far more details than ever before.

By measuring how the planet's brightness changes as it moves through different phases - or positions - around its orbit, we now start to learn more about its atmosphere as a whole, both on the dayside and the nightside.

Preliminary results tend to indicate that it may be much colder than previously thought on the nightside that clouds made of sand-like material could form.

We don't really know how it all works, why it is so hot and clear on the dayside while it is so cold and cloudy on the nightside. We need to analyse the observations further.

And to understand them better, we need to rely on (super-)computer simulations, which take into account all these exotic processes that do not exist on Earth.

We will be using the Met Office Unified Model, which is a computer model that is normally used to simulate and predict the weather and climate on Earth, but has been adapted over the past few years to the weather and climate of other planets.

It is one of the most sophisticated and accurate weather and climate models in the world, and will help us to better understand the complex processes that drive the weather and climate on WASP-121b.