Artist’s impression of an exoplanet with a magnetic field. Credit: ESO Picture a planet with no sunrise and no sunset. One hemisphere is scorched by a star it can never turn away from. The other is locked in permanent night. Between them, colossal winds rip through the atmosphere at thousands of miles per hour, fast enough to make Jupiter’s worst storms look almost tame. These are ultra-hot Jupiters, some of the most extreme planets we know of.