Quote Originally Posted by krunchyfrogg View Post
Not much, to be honest. This characters god is the god of the stars, so I wanted to make sure his priest would know what he’s looking at.
Then that's mostly non-mechanical. You can just say that he knows the stars--I wouldn't make you roll for it except under exceptional circumstances.

Quote Originally Posted by lunaticfringe View Post
Since it ties into your PC's faith I'd use Religion or Nav Tools depending on what you were trying to do.
Quote Originally Posted by Unoriginal View Post
Arcana would work, too, because several stars in D&D are actually beings such as Great Old Ones.
I see skills as being much more related to the use of the knowledge. Are you trying to navigate? Then Navigator's Tools. Are you trying to determine the religious significance of a pattern? Religion. Are you trying to determine the magical significance? Arcana. Are you just knowing the stars for role-play purposes? No skill needed. Just like you don't need History to know the leader of the town you grew up in.