We cross the galactic current sheet about once every 12,000 years.
The current sheet sweeps up dust and debris like a Swiffer duster. Some small fraction of this dust is bigger than dust; sand, gravel, rocks, boulders, and the occasional really, really big rock.
Most of that crap passes through the Solar system without actually hitting anything. Most, but not all.
About every 12,000 years. The last big chunk to hit earth was about 13,000 years ago. We haven't quite hit the dust storm yet...
SMOD 2024!!!