Hot Jupiters are exoplanets that are similar in size and composition to the Jupiter in our solar system, but their close orbital period around their host star makes them hot! Really hot. Scientists are studying exoplanets like WASP-121b, which are known as “ultra-hot Jupiters,” They are tidally locked to their host star the way our moon is locked to the Earth, and one face of the planet is always facing its star. That means that the day side is constantly scorched. Scientists thought these types of exoplanets might be able to hold onto water molecules but new data shows that the day sides are so hot and irradiated that whatever water molecules might exist get ripped apart before getting swept away onto the planet’s night side. Scientists think the recondensed water molecules then form into clouds that get swept back to the day side only to get destroyed again.