Lunar Swirls Unveil the Origin of the Moon Magnetic Field

TL;DR

This study proposes that ancient electrical currents generated by the lunar interior's dynamo activity created magnetic anomalies and swirls on the Moon, revealing a new understanding of lunar magnetism.

Contribution

It introduces a novel model linking ancient electrical currents to lunar magnetic anomalies, supported by 3-D mapping and magnetic-electric field simulations.

Findings

Ancient currents could reach densities of 13 A/m2.

Surface magnetizing fields as strong as 469 μT were generated.

Lunar swirls are caused by electrical discharges from the interior dynamo.

Abstract

The origins of the lunar magnetic anomalies and swirls have long puzzled scientists.The prevailing theory posits that an ancient lunar dynamo core field magnetized extralunar meteoritic materials, leading to the current remnant magnetic anomalies that shield against solar wind ions, thereby contributing to the formation of lunar swirls. Our research reveals that these lunar swirls are the result of ancient electrical currents that traversed the Moon's surface, generating powerful magnetizing fields impacting both native lunar rocks and extralunar projectile materials. We have reconstructed 3-D distribution maps of these ancient subsurface currents and developed coupling models of magnetic and electric fields that take into account the subsurface density in the prominent lunar maria and basins. Our simulations suggest these ancient currents could have reached density up to 13 A/m2, with surface magnetizing field as strong as 469 {\mu}T. We propose that these intense electrical current discharges in the crust originate from ancient interior dynamo activity.