WHAT I WANTED TO DO:
Create a 2D, geometric design that appears to have some cosmological meaning but that in reality is complete bullshit.
WHAT I LEARNED:
How to use the shape builder tool to make circular cuts into objects.
WHAT I DID:
The last crescent moon-looking thing was made by literally eclipsing the planet with an opaque circle. I could figure out how to make a circular cut.
Now I know it’s as simple as getting the shape builder, imposing a circular shape over the object I want cut, selecting all, then “clipping” out what I don’t want.