What Am I Riddles

Question: I move around yet one side is hidden while another is shining. I can be seen full but only sometimes. What am I?

Question: Turn us on our backs and open up our stomachs You will be the wisest. What am I?

Question: The more you cut into me the bigger I grow, what am I?

Question: Silent yet deafening. Invisible, but you know it's there. It can either make you laugh or it can make you cry. What is it?

Question: Without me, nothing exists. What am I?