Magnetic field of the Moon

The magnetic field of the Moon is very weak in comparison to that of the Earth; the major difference is the Moon does not have a dipolar magnetic field currently (as would be generated by a geodynamo in its core), so that the magnetization present is varied (see picture) and its origin is almost entirely crustal in location; so it's difficult to compare as a percentage to Earth. But, one experiment discovered that lunar rocks formed 1 - 2.5 billion years ago were created in a field of about 5 microtesla (μT), compared to present day Earth's 50 μT. During the Apollo program several magnetic field strength readings were taken with readings ranging from a low of 6γ (6nT) at the Apollo 15 site to a maximum of 313γ (0.31μT) at the Apollo 16 site, note these readings were recorded in gammas(γ) a now outdated unit of magnetic flux density equivalent to 1nT. One hypothesis holds that the crustal magnetizations were acquired early in lunar history when a geodynamo was still operating.

Source: Wikipedia — Magnetic field of the Moon (CC BY-SA 4.0)