Lunar rocks collected by Apollo astronauts more than 50 years ago are shedding new light on the moon’s mysterious magnetic field, revealing short but intense bursts of magnetism that may have rivaled Earth’s billions of years ago.
Researchers at the University of Oxford analyzed the titanium-rich lunar rocks and discovered that the moon’s magnetic field, generally weak over most of its history, experienced brief spikes lasting from a few decades up to 5,000 years. These surges likely resulted from molten, titanium-heavy rocks deep within the moon, according to lead author Claire Nichols.
“These spikes are incredibly short-lived compared with what we expected,” Nichols said. “It shows that lunar magnetic activity was far more variable than previously thought.”
The findings, published in Nature Geoscience, challenge earlier theories suggesting the moon maintained a steady magnetic field for long periods. The Apollo samples, taken primarily from low-latitude lava plains rich in titanium, may not represent the moon’s overall magnetic history, the researchers noted.
Future lunar missions, particularly NASA’s Artemis program, aim to explore new regions such as the moon’s south pole, where permanently shadowed craters could contain ancient rocks and water ice. Four Artemis astronauts are scheduled to orbit the moon in a critical test flight possibly as early as April, with future surface missions expected to collect additional samples to deepen our understanding of lunar magnetism.
Magnetic fields are essential for shielding planetary surfaces from cosmic and solar radiation, a factor in considering planetary habitability. Studying the moon’s intermittent magnetic strength could also offer insights into how rocky planets develop and maintain protective magnetic shields.
Nichols and her team found a correlation between high titanium concentrations and preserved magnetic signals, suggesting a key role for titanium-rich rocks in generating intense, albeit short-lived, magnetic episodes. Rocks from the Apollo 11 and Apollo 17 missions contained the most titanium and the strongest traces of magnetism.
“By analyzing both the oldest and newest Apollo samples, we’ve identified a missing link in understanding lunar magnetism,” Nichols said. “These results will guide future Artemis missions in exploring the moon’s magnetic past and its implications for planetary science.”