Moon's mighty magnetic field was a 5,000-year titanium blip

The Register

February 26, 2026

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The Moon's strong magnetic field, once thought to persist for billions of years based on Apollo mission samples, was actually a brief and rare phenomenon lasting only about 5,000 years, according to new research from the University of Oxford. By analyzing Mare basalts—lunar rocks rich in titanium—the study reveals that periods of intense magnetism were linked to the melting of titanium-rich material near the Moon's core-mantle boundary. These events generated strong magnetic fields for short durations, challenging previous interpretations that suggested a long history of robust lunar magnetism. The bias in Apollo samples, which disproportionately collected high-titanium rocks from flat regions like Mare basalts, led scientists to overestimate the duration of these intense magnetic periods. The study highlights that the Moon's magnetic field was typically weak for most of its history, aligning with dynamo theory, which predicts that small planetary cores struggle to sustain strong magnetic fields. The brief bursts of magnetism were likely tied to unique geological events involving titanium-rich melts. This discovery resolves a decades-long debate about the Moon's magnetic past and underscores the importance of sample bias in interpreting planetary geology. It also offers new insights into how magnetic fields behave on small, airless bodies like the Moon. For future lunar missions, such as NASA's Artemis program, this research will help guide sample selection to better understand the Moon's magnetic history. The findings not only refine our understanding of lunar evolution but also have implications for studying other planetary bodies. By identifying how rare and short-lived strong magnetic events were on the Moon, scientists gain a new perspective on the mechanisms behind magnetic field generation in the solar system. This knowledge could inform future exploration and

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Originally published on The Register on 2/26/2026