The moon (as do all moving bodies), is travelling in a straight line point A to point B. Point B however is relocated to point C as the mass of Earth collapses the distance from D to B. This space contraction is continuous throughout the orbit and gives the illusion that the Moon is travelling in a circle. The Moon is trapped forever and moves along a line beginning and ending
at point A. The space along this line is wrapped around the mass of the Earth
.......Simples.