NASA scientists have shed new light on a long-standing mystery surrounding the origins of the Moon’s magnetic field. Analysis of lunar rock samples suggests that strong magnetic fields similar to those found on Earth existed in the early days of the Moon, but their source remains unclear.
Research published by MIT scientists in the journal Science Advances proposes that a massive asteroid impact briefly boosted the Moon’s weak magnetic field, leaving behind a record of this spike in some samples. This idea is supported by recent findings from China’s Chang’e 5 and Chang’e 6 missions, which suggest that the early Moon had at least a weak magnetic field.
However, the question remains: how did the Moon’s magnetic field form? Typically, strong magnetic fields develop through the process of dynamo, where molten metals in the core convect due to heat dissipation. However, the early Moon’s small core lacked sufficient cooling to induce significant convection and thus a robust dynamo.
Scientists have proposed various theories to explain the Moon’s magnetic field origin, including the idea that massive rock formation during its molten phase generated a core with alternating strong and weak fields. Another theory suggests that the impact of meteorites or comets may be responsible for the magnetic signature observed in some samples.
Source: https://arstechnica.com/science/2025/05/have-we-finally-solved-mystery-of-magnetic-moon-rocks