Magnetized Rock on Moon's Far Side Backs Ancient Lunar Dynamo

Researchers at ETH Zurich found a strongly magnetized rock about 60 km wide in the Dewar region on the Moon's far side, likely solidified magma roughly 4.2 billion years old. Joint modeling of gravity and magnetic data suggests an early lunar dynamo with a field of about 11 microteslas.

• 60-km-wide Dewar rock is likely magma solidified 4.2 billion years ago
• Estimated ancient lunar field strength was about 11 microteslas vs Earth's 50
• The magnetic anomaly coincides with a gravity anomaly and a lunar swirl
• Findings come from archived orbital data, not returned samples