Create an interactive galaxy map for a game

We are in the early process of creating an online space-based game. To get ball rolling we need an interactive map of a fictional galaxy - the galaxy will have hundreds/thousands of stars with should be connected by specific paths. The stars should be in clusters of between 20-100 which are connected to other clusters using specific paths. We should be able to add to and edit the galaxy as an when we need to. The map of the Galaxy should work a bit like google maps (tiles) so the user can zoom and select stars. The map also needs to be able to pathfind - if a user wants to create a route between "a" and "c" the map should show the shortest route. Ideally this should use html/JavaScript and should be programmable so we can write scripts to integrate with the map.