Buried Structure on Moon's Far Side Points to Ancient Lunar Dynamo

Researchers combined GRAIL gravity data with magnetic measurements from Lunar Prospector and Kaguya to find a dense, strongly magnetized body about 60 km wide and 9 km deep in the Dewar region. The ancient lunar field likely exceeded 10 microtesla, supporting the case for a dynamo 4.2 billion years ago.

• Dewar structure is about 60 km wide and 9 km deep
• Ancient lunar magnetic field estimated above 10 microtesla
• Magnetized body is solidified magma roughly 4.2 billion years old
• Data came from GRAIL gravity and Lunar Prospector and Kaguya magnetometry