The far side of the Moon provides clues to a previous magnetic field

Researchers at ETH Zurich analyzed gravity and magnetic field measurements from the Moon's far side to conclude that the Moon possessed an internally generated magnetic field approximately 4.2 billion years ago, with strength between one-fifth and one-third of Earth's current magnetic field. Using orbital probe data rather than contradictory rock samples, the study supports the theory that the Moon operated a dynamo mechanism similar to Earth's core-generated magnetic field, though it no longer functions today.