[dayglored]

> A simpler explanation would be that the far side of the moon is exposed to deep space and whatever may be hurled at it, while the near side of the moon is shielded from all of that by the earth.

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.

[CurlyDave]

...It's 8,000 miles in diameter, certainly bigger than the Moon, but it's 300,000 miles distant...

I learned 240,000 miles in grade school (in the 1950s) and I do not believe it has changed since them.

But I do agree with you on the "insignificant shielding" issue.

[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.