I think there's a simpler way to name it, but completely fails to define it. 1a-1-1 (first galaxy, first galactic arm, first star, first planet in the system) All of it's the first, it's easy that way. (edit) I realized this system is very likely to hurt other aliens' state of mind. As such, I make a new name system: Greenway-Carl-Prals47-Earth (galaxy name, galactic arm name, star name, planet name) If we turn out on the top of space development, I think it's fair to say that we can call the galaxy Greenway (out of sheer military power).