Lunar magnetism: Exploring the origin of lunar magnetic anomalies through the Parker Inversion method

Abstract

Lunar magnetism has remained an unsolved mystery since the Apollo days, with its origin debated between an internal core-dynamo or transient magnetic fields from impacts. While most investigations studying magnetic anomalies with orbital data use methodologies inherently limited by relying on available geological/geophysical context, this study overcomes these constraints with a novel approach. It implements the versatile Parker Inversion method to estimate the spatial distribution, intensity, and direction of surface magnetization. Correlative analyses of the results with impact-related processes indicate a prominent role of impacts in shaping lunar magnetism: most isolated near-side anomalies are probably magnetized ejecta from the Imbrium impact, while complex far-side and North Pole anomalies likely originate from antipodal effects of Imbrian and Nectarian-aged impacts. Magnetized material also strongly correlates with lunar swirls. Findings overall suggest that a transient origin alone is unlikely, favoring a core-dynamo as the primary magnetic field source, potentially amplified by impact events.