What are the origins of Moon Mascons?

[Russell_B]

I've come to understand that the moon has, beneath its surface, mass concentrations (masscons) that cause an orbiting craft to take a rather irregular orbit, and 'dip' when it passes over these areas.

Do we know what these masscons are comprised of?

If not, what are the most feasible predictions?

Russ

 

[Kracatoan]

Mascons were created when the Moon was very young. In those days it still had a liquid core made of very dense rock. The surface was not as solid as it is now and much less dense. Whenever large asteroids and suchlike hit the moon they blasted away large craters of the less dense rock which were then filled by the molten dense rock rising up to fill the crater. Since then the Moon has cooled so the core is solid so no more mascons can form.