New Study Reveals the Ancient Moon Hid an Ocean of Magma in Its Mantle
Staring up at the moon on a clear night is generally a very cool and calming experience, but according to a group of scientists, the interior of la luna was once as far from cool and calm as could be.
According to new research published in the journal Earth and Planetary Science Letters, some 4 billion years ago, our planet's nightlight (and the thing responsible for tidal friction, etc.) may have held an ocean of molten magma in its mantle, the layer between the core and crust.
"Theoretical work invoking a core dynamo has been unable to explain the magnitude of the observed field, falling instead one to two orders of magnitude below it," Aaron L.Scheinberg and his co-authors wrote.
"Since surface magnetic field strength is highly sensitive to the depth and size of the dynamo region, we instead hypothesize that the early lunar dynamo was driven by convection in a basal magma ocean formed from the final stages of an early lunar magma ocean."
The recent study focused on what may have created the magnetic field around the moon.
Co-author Krista Soderlund explained to Live Science that it takes three things to create a magnetic field: a liquid, motion and electric conductivity.
Image credit: Aaron Scheinberg
The movement of Earth's metallic core creates its strong magnetic field. The researchers say that the moon's core is not large enough to have created the strong magnetic field that was recorded in ancient moon rocks collected during Apollo missions in the 1960s and '70s.
When the molten ocean cooled and solidified, the field became the significantly weaker one that the moon has today.
"It's like a natural evolution of the moon's cooling that we're able to have this sequential type of magnetic field generation," said Soderlund.
"We're excited by this result because it explains fundamental observations about the Moon—its early, strong magnetic field and its subsequent weakening and then disappearance—using first-order processes already supported by other observations," co-author Elkins-Tanton said.