Not exactly breaking news!
But, kinda cool!
A conventional compass would be of little use on the moon, which today lacks a global magnetic field.
But the moon did produce a magnetic field billions of years ago, and it was likely even stronger than the Earth’s field today. Scientists believe that this lunar field, like Earth’s, was generated by a powerful dynamo—the churning of the moon’s core. At some point, this dynamo, and the magnetic field it generated, petered out.
Now scientists from MIT and elsewhere have pinned down the timing of the lunar dynamo’s end, to around 1 billion years ago. The findings appear today in the journal Science Advances.
The new timing rules out some theories for what drove the lunar dynamo in its later stages and favors one particular mechanism: core crystallization. As the moon’s inner iron core crystallized, the liquid core’s electrically charged fluid was buoyantly stirred, producing the dynamo
“The magnetic field is this nebulous thing that pervades space, like an invisible force field……….. We’ve shown that the dynamo that produced the moon’s magnetic field died somewhere between 1.5 and 1 billion years ago, and seems to have been powered in an Earth-like way.”Benjamin Weiss
Weiss’ co-authors on the paper are co-lead authors Saied Mighani and Huapei Wang, as well as Caue Borlina and Claire Nichols of MIT, along with David Shuster of the University of California at Berkeley.