A recent study from scientists at NASA and the University of Arizona found that a layer of low-viscosity goo sits between the Moon’s rugged mantle and its metal core. This goo is rising and falling beneath the lunar surface — not unlike, say, ocean tides — which they concluded is likely caused by the gravitational push and pull of the Sun and Earth.

I wonder if it has to be a partial melt. We are finding that many asteroids are loosely bundled rocks. I wonder if maybe the moon has a similar structure. I have no clue how much pressure is under the surface and off it’s enough to fuse everything together.