Long ago, the Moon likely had a global magnetic field. As the core cooled, the field weakened and vanished. Some rocks cooled while magnetized and preserved that orientation. These patches can deflect solar wind. They create localized magnetic bubbles. Scientists call them magnetic anomalies.
This matters because magnetism protects surfaces from radiation. These regions weather differently. They may preserve ancient material.
It also challenges assumptions about small bodies. Even small worlds can generate magnetic dynamos—temporarily.
The Moon’s strongest magnetic regions are found on the far side. They’re invisible from Earth.
NASA [nasa.gov]