The moon lacks a magnetic field today, yet some rocks on its surface are strongly magnetized. Scientists have been puzzled by this phenomenon for decades. A recent study suggests that an ancient asteroid impact may be responsible. The research team, led by graduate student Isaac Narrett, used computer simulations to explore the possibility of a massive asteroid impact billions of years ago briefly amplifying the moon’s weak magnetic field.
The simulations indicate that such an event could have vaporized surface material and created a cloud of electrically charged particles called plasma. As the plasma enveloped the moon, it would have concentrated on one side, temporarily enhancing the magnetic field in that area. Rocks in the region could have captured this short-lived magnetic surge before the field faded away.
The researchers estimate the entire sequence occurred within an hour and left behind a detectable magnetic signature. The findings explain the strong magnetic fields measured by orbiting spacecraft, especially on the far side of the moon. According to Narrett, “the majority of the strong magnetic fields can be explained by this process.”
The team’s theory is supported by the fact that the most strongly magnetized rocks lie near the south pole, on the farside. Future missions, including NASA’s Artemis program, plan to explore these areas in the coming years. The study was published in Science Advances and offers new insights into the moon’s magnetic anomalies.
If confirmed, this theory would provide a significant explanation for the moon’s unusual magnetic rocks. Narrett noted that “there are large parts of lunar magnetism that are still unexplained.”
Source: https://www.space.com/astronomy/moon/the-moon-doesnt-have-a-magnetic-field-so-why-does-it-have-magnetic-rocks