explanation of mechanism of moon capturing

[Airbrush]

How about the idea that the Moon formed in an orbit so near Earth that at some point the two were moving at a slow speed relative to each other.  Then the Moon, which is inside of Earth's orbit, passed by the Earth too close and the Earth acted to slow down the Moon, whipping it around the Earth, and capture it in orbit?  How could that not have happened?

I do believe astronomers think the best Moon creation theory is the giant impact of Thea but I'm not sure why.

Edited May 7, 2018 by Airbrush

[Airbrush]

"The Moon formed 4.51 billion years ago,^[f] some 60 million years after the origin of the Solar System. Several forming mechanisms have been proposed,^[26] including the fission of the Moon from Earth's crust through centrifugal force^[27] (which would require too great an initial spin of Earth),^[28] the gravitational capture of a pre-formed Moon^[29] (which would require an unfeasibly extended atmosphere of Earth to dissipate the energy of the passing Moon),^[28] and the co-formation of Earth and the Moon together in the primordial accretion disk (which does not explain the depletion of metals in the Moon).^[28] These hypotheses also cannot account for the high angular momentum of the Earth–Moon system.^[30]

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The evolution of the Moon and a tour of the Moon

The prevailing hypothesis is that the Earth–Moon system formed after an impact of a Mars-sized body (named Theia) with the proto-Earth (giant impact). The impact blasted material into Earth's orbit and then the material accreted and formed the Moon."

https://en.wikipedia.org/wiki/Moon#Formation