On the History of the Lunar Orbit

In this paper, the data relevant to the construction of an evolution curve of the lunar orbit are col- lected. The data on the gravitational field of the Moon are used to determine a "reference" point in the evolution curve of the lunar orbit, c ~ 21.6 R at t ~ 4 Ga (billion years ago), where c is the distance between the centers of the Earth and the Moon and R is the Earth's radius. The averaged evolution curve c(t) consists of two straight- line segments with a mean velocity of 3.68 cm/yr in the range from 0.9 Ga to the present time, and 6.87 cm/yr in the range from ~4 to 0.9 Ga. The largest uncertainty is still retained for the epoch of formation, existence, and fragmentation of the first supercontinent Rodinia (at ~1 ± 0.2 Ga), in the zone of joining the straight-line segments that describe, on average, the evolution curve of the lunar orbit. The analysis performed leads to the conclusion that a global ocean existed at 4 Ga on the surface of the Earth. Approximately at that time, a system- atic growth of the continental segment on the surface of the Earth began. Before the onset of the growth of the Earth's continental segment, a retreat of the Moon from the Earth was determined by tidal friction in terrestrial tides. The increase in the surface area of the continental crust and shallow seas after ~4 Ga led to the domination of friction in ocean tides, which determined the evolution of the lunar orbit during all subsequent epochs.