Flows of molten metal can generate magnetic fields. This so-called dynamo effect creates cosmic magnetic fields, like those found on planets, moons and even asteroids. In the coming years, researchers are conducting a unique experiment in which a steel drum containing several tons of liquid sodium rotates around two axes in order to demonstrate this effect. It will be carried out in the new DRESDYN facility at the Helmholtz-Zentrum Dresden-Rossendorf (HZDR), an independent German research laboratory. A study, recently published in Physical Review Letters, reports the experiment’s chances of success.