Fact #171
Earth & tides
It works both ways. Earth's pull flexes the solid body of the Moon by about ten centimetres, twice per orbit, and that flexing is measurable from here.
Because the Moon's orbit is elliptical the pull is not constant, so the rock kneads slightly as it goes round. Laser ranging picks the deformation up, and how much the Moon gives tells you how soft its interior is — which is a large part of the evidence for a partly molten layer deep inside it.
Source: Williams & Boggs, J. Geophys. Res. Planets 120, 689 (2015) · checked Sep 2026