A recent study by NASA and the University of Arizona has revealed a surprising discovery about the moon’s interior. Researchers have found a low-viscosity layer between the moon’s rocky mantle and its metallic core. This blob moves up and down beneath the surface, similar to the tides of Earth’s oceans. They believe this movement is driven by the gravitational forces of the Earth and the sun, they report futurisme.com.
“Just as the moon raises the tides on Earth, the Earth (and the sun) raises the tides on the moon,” the study explains. The study, published in AGU Advances, provides the “first measurement of the moon’s annual gravitational changes due to tides.”
This discovery supports long-standing theories about the moon’s composition, but also raises new questions. How did this magma-like layer form? What exactly is it made of? And most importantly, what keeps it warm enough to stay soft and mobile?
The researchers analyzed data from NASA’s Gravity Recovery and Interior Laboratory (GRAIL) and Lunar Reconnaissance Orbiter missions. These missions collected gravity data and mapped the moon’s surface, allowing scientists for the first time to measure tidal movements on both a monthly and annual basis.
Their findings indicate a “partial melt layer” beneath the moon’s rocky mantle, which is made of magnesium-iron silicate minerals and pyroxene.
“Only models with a softer layer at the bottom of the mantle agree with all our measurements,” the researchers noted.
But this raises an important question: what keeps this semi-melted layer warm and pliable? As the study shows, “such a soft layer, which is often thought to partially melt, must be preserved.” There must be a reason why this layer stays warm enough to move.
There are still many unknowns about the moon’s interior, but this research marks an important step forward. It opens the door to future discoveries in lunar geology.
As the study concludes, “The existence of this zone has profound implications for the moon’s thermal state and evolution.”
