Overview
- Researchers report a roughly 60-kilometre-wide, up to 9-km-deep dense magmatic body beneath the Dewar region on the Moon’s far side that carries strong remanent magnetization.
- The team used a new 3D joint inversion that combined NASA GRAIL gravity data with magnetometer measurements from Lunar Prospector and Japan’s Kaguya to estimate both subsurface density and magnetization at once.
- Modeling tied the magnetization to overlying impact deposits dated to about 4.2 billion years ago and yields a paleofield of at least 11 microtesla, with local estimates up to roughly 22 microtesla.
- The buried, horizontally magnetized body offers a plausible cause for nearby Lunar Swirls by deflecting the solar wind and it may point to local magnetic zones that could partly shield future astronauts.
- The finding, reported in Science Advances and covered this week, strengthens the case for a long-lived, internally generated lunar dynamo but leaves open the key question of how the small lunar core sustained that field and when it shut down.