How do I blend and transition between skyboxes?

I want to blend several skyboxes together. I want to take a day skybox, then transition to a night skybox. I want the night skybox then have a star skybox blended with it partway through the night. Next I want it to fade out and then have the night skybox transition to the day skybox. I also want all of the skyboxes to rotate. These are the skyboxes I am using:

Day and Night skyboxes

Star Skybox

Skybox is just a material with a shader. You can write a custom shader that blends between two textures, combine it with some procedural layer, or pretty much anything that you can do with shaders.