Mysterious Subsurface Feature Displaying Unusually Strong Magnetism on the Far Side of the Moon May Solve 4.2-Billion-Year-Old Mystery

Researchers found a mysterious subsurface feature on the Moon’s far side that displays unusually strong magnetism, suggesting the Moon may have had an ancient magnetic field similar to Earth’s 4.2 billion years ago. The study, led by ETH Zurich and involving researchers from DLR and TU Berlin, used gravity and magnetic data from the Dewar crater to model the region. The feature, which is 60 kilometers wide and nine kilometers deep, is composed of dense, magnetized rock. The findings support the dynamo theory, which proposes that the Moon once had a rotating iron core capable of generating a magnetic field.

• The team’s models indicate the subsurface feature is a solidified magma body, consistent with an ancient molten core.
• The magnetic and gravity data suggest the feature is a buried volcanic complex, and its composition and age were determined from impact materials.
• The study estimates the magnetic field strength at 10 microtesla, much stronger than Earth’s current 50 microtesla.

The research challenges previous theories that lunar magnetism could result from meteor impacts. It suggests the Moon’s magnetic field was stronger in the past and may have originated from a long-lasting dynamo in its core. While the exact mechanism remains unclear, the findings provide new insights into the Moon’s internal structure and history. The study was published in *Science Advances* and is expected to influence future research on lunar geophysics.

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