The existence of “hot Jupiters” is one of the oldest mysteries of the exoplanet-hunting era, but a European spacecraft is revealing some clues about how these enigmatic worlds form.
So-called hot Jupiters are planets that are roughly as massive as Jupiter and orbit very close to their stars, usually less than one-tenth the distance at which Earth orbits the sun. Hot Jupiters are very different from anything seen in the solar system, posing questions about their formation.
