moons magnetic secret

The Moon’s Mysterious Magnetic Field

Photo credit: Mark A. Wieczorek

The Moon has remained magnetically inert for eons, but new research confirms that this was not always the case. Over four billion years ago, an inner molten moon-core whirled against a lunar mantle, much like Earth’s own dynamo, and a potent magnetic shield extended from the Moon. But this was presumably a much weaker version than Earth’s, since the satellite obviously lack’s Earth’s heft, right?

Surprisingly, our scrawny little moon was actually able to generate a mightier field than ours. No one knows why such a puny body displayed such potent magnetic activity, with current answers running the gamut from “we don’t know” to “magic?” The mystery reveals that there’s yet another unknown set of variables regarding our most intimately studied partner. It appears the early Moon took advantage of some exotic method to produce its awesome magnetic field. And it managed this for longer than astronomers previously thought was possible, perhaps due to constant meteor impacts that fueled Luna’s magnetism.

It appears that the field disappeared sometime around 3.8–4 billion years ago, though more research is necessary to find out exactly why. Surprisingly, studies suggest that the Moon’s core is still at leastslightly liquid. So even though the Moon is within reaching distance, we’re constantly reminded that there are many fundamental questions we’ve yet to answer about lunar geology.