Answer:
By Moon or by Sun I shall be found. Yet I am undone if there's no light around.
I hide but my head is outside. What am I?
When you stop and look, you can always see me. If you try to touch, you cannot feel me. I cannot move, but as you near me, I will move away from you. What am I?
I am what brings things together. Without me everything you see would be a total mass or debris everywhere. What am I?
I am black, white, and read all over. What am I?
No matter how little or how much you use me, you change me every month.