This cover has two components. The round object is a small bowl that my mother made back in the 1950s. When it was newly from the kiln, the glaze on the bottom "crazed."
I was nearby when it happened -- it made a noise.
I suggested to Ruth that the bowl might work, and she agreed. When I had a bowl image that satisfied me (the shadow was crucial) I dropped it on a night sky photograph I already had.
Crazing