[MonkeyClub]

I have the same question, if anyone knows the answer it'd be awesome.

I mean, sure, simply by virtue of the moon's being there, it sort of fends some stuff off like a fence.

But beyond that, is its gravitational pull adequate to affect trajectories?

If so, wouldn't earth's trump it? (Although the inverse square here may play a big part, but that would also make me more inclined to disregard the moon's gravity pull as assisting in any protection it otherwise naturally affords.)

Edit: clarified (?) thought

[h2odragon]

I think the effect of the moon is not so much "catching" things as it is perturbing orbits near earth such that things either crash into earth or moon or get flung away.

Without the moon we might have a lot more stuff in solar orbits that overlap earths orbit.

I expect this could be explained better (and I may well be totally wrong).

[thehappypm]

It’s really more that the moon has no atmosphere. A shooting star on Earth would be a crater on the moon.

[krapp]

Ackshually, the moon has a very thin atmosphere, primarily composed of neon, helium and hydrogen.

[outworlder]

Not enough to matter for most purposes.

[mannykannot]

The first requirement for a piece of space junk to hit the moon is to be on an orbit that will cross the moon's. Most space junk is left over from launching things into earth orbit (geostationary or lower), and so will not be going fast enough.