Scrolling down, I see that JET is hung up on day and night without sun. To me, this is one of the most fascinating aspects of Creation. Think about it, there is also light without sun! Love it!
If you think of the spectrum of light, we now know that we only "see" a tiny portion of it. And yet it is all light. Gamma rays, xrays, yada yada. It's all LIGHT! And God said, "Let there be Light." Big Bang? Works for me? Pure energy. Light. No sun.
As to day and night with no sun....TIME. The creation of time. The sun, moon and stars give a means to measure time, but time, came first. So cool!