Moon had magnetic field at least a billion years longer than thought – study

Even small planets could have long-lived magnetic fields, crucial for atmosphere and water, raising fresh possibilities in the hunt for new worlds

The moon's magnetic field lasted at least a billion years longer than previously thought, researchers have revealed, shedding light on an enduring lunar mystery and expanding the possibilities in the hunt for habitable worlds beyond Earth.

Nowadays, the moon has no global magnetic field, but that was not always the case; between 4.25bn and 3.56bn years ago, the lunar magnetic field was similar to that of the Earth. The field is thought to have been generated by the churning movement of fluids within the moon's molten core - a sort of lunar dynamo.