That is not a small project!
I would suggest that you have a look here:
Google: "star map software c#"[
^] - it has been done before, and even if none of the info is exactly relevent to how you want to do it, it should at least give you ides of how to proceed. Have a good look at the link Google gives to
Stellarium[
^] - it's open source, and may give you some useful ideas.
Good luck! (I think you have a lot of work ahead of you...)