Caption: A cartoon of space weathering.

Features:

1. Space weathering is the kind of weathering on objects (especially importantly airless worlds) exposed to outer space.

2. Space weathering processes:
   1. Impacts by meteorites including micrometeorites.
   2. Irradiation by cosmic rays (CRs).
   3. Exposure to solar winds in the Solar System and, speaking generally, stellar winds in planetary systems in general. Sputtering can occur.
   4. Diurnal temperature cycle weathering which fragments rock through repeated cycles of expansion and contraction with temperature Note there are extreme daily temperature fluctuations on airless worlds. This process is NOT usually considered part of space weathering, but it makes sense to do so since it happens in the same places as the other processes with similar effects to process 1 above.

3. Processes 1 and 4 are particularly important in pounding down the surfaces of airless worlds to regolith. Such airless-world regolith often gives a smooth appearance and typically it seems has a large component of slippery, spherical vitreous (i.e., glassy) dust. This dust is slippery because it's like little ball bearings. At least lunar soil is like this. See Wikipedia: Lunar Soil: Mineralogy and composition and Popular Science, 1972, December, p. 64, Last Apollo Will Put First Scientest on the Moon.