Unlike Earth, the moon no longer has a core-generated magnetic field. On our planet, the movement of liquid iron in the outer core generates a global magnetic field. This so-called geodynamo works on a similar principle to a bicycle dynamo, which converts mechanical motion into electrical energy. “Today, there is an ongoing heated debate as to whether the moon also operated a dynamo in the past,” says Xi Yang, a Ph.D. student in the Department of Earth and Planetary Sciences at ETH Zurich. This is because analyses of rock samples brought back to Earth by the Apollo astronauts are contradictory.
