New Study Says Moon's Magnetic Field Existed 1 Billion Years Longer Than We Thought

“You see how magnetized it gets from getting heated in that known magnetic field, then you compare that field to the natural magnetic field you measured beforehand, and from that you can figure out what the ancient field strength was... In this way, we finally have gotten an accurate measurement of the lunar field."

“The concept of a planetary magnetic field produced by moving liquid metal is an idea that is really only a few decades old. What powers this motion on Earth and other bodies, particularly on the moon, is not well-understood. We can figure this out by knowing the lifetime of the lunar dynamo.”

“As the moon cools, its core acts like a lava lamp - low-density stuff rises because it’s hot or because its composition is different from that of the surrounding fluid. That’s how we think the Earth’s dynamo works, and that’s what we suggest the late lunar dynamo was doing as well... Today the moon’s field is essentially zero. And we now know it turned off somewhere between the formation of this rock and today.”