Explanation for the Two-Faced Moon: Colossal Ancient Impact Linked to Differences Between the Moon’s Near and Far Sides

scitechdaily.com ^ | APRIL 10, 2022 | BROWN UNIVERSITY

[Verginius Rufus]

So that’s what KREEP is. Sam Ervin’s Senate committee kept talking about it in 1973.

[Svartalfiar]

Nope, the Earth doesn't provide significant shielding for the Moon. It's 8,000 miles in diameter, certainly bigger than the Moon, but it's 300,000 miles distant, meaning it provides a pretty much negligible barrier to space rocks. Visualize 8 vs. 300 -- it's like an 8-inch pie plate at a distance of 25 feet.

But the Earth's gravitational field is much bigger. So for any rock coming at the moon from the Earth-side, there's a small circle around Earth that the rock has to hit to be swung into the Moon, otherwise it misses. Needs an exact velocity on the proper vector, whereas rocks hitting the other side only need to be on the right vector, velocity doesn't matter.

No idea how much that actually affects the odds, but it seems like it would narrow them somewhat.

[dayglored]

Yep, ~240,000 not ~300,000. I was misremembering.