Can't see Sun, Moon, clouds and stars.

When I go into a world I can't see the sun or the clouds it's just a blue sky. I can see the colors the sun makes when it's risking but I can't see the sun. When it's night I can't see the moon or stars it's just a black sky. I used to be able to see the sun,moon,clouds, and stars but now I can't. I have tried going into old worlds to see if it's just the new ones that's being weird but it didn't work the sky is still blank.