ChronoBlender sun/moon cycle for background layer
add this setup as a background layer
make all layers with objects active

This setup allows the moon to use transparency to
block the sun, like an eclipse.

Moon fades away as the day goes by
Moon has phases via the sun
Sun rotates counter-clockwise
Moon  can have rotation offset to allow different
orbits (multiple moons)
Sky Fades to show stars

Sun's parent must have sun material
Moon's parent must have sky material
All materials are set properly
Any deviation could result in the moon cutting
through all objects.
Textures in the materials should be replaceable