G'day Sam,
I am still working on some recommendations for textbooks on each of the various aspects of astronomy, but if you need to get an overview of astronomy that is more detailed and more accurate than a General Astronomy textbook, I strongly recommend that you get "The Astronomy and Astrophysics Encyclopedia", edited by Steven P. Maran : :
http://www.amazon.com/Astronomy-Astr...s+encyclopedia
(I have reviewed it, at this amazon.com page)
(NOTE: THERE IS ANOTHER REFERENCE BOOK IN EXISTENCE WITH NEARLY THE SAME NAME)
While this book uses little mathematics, it has a strongly physical approach which imparts detailed and structured understanding. Much better than any of the introductory university astronomy textbooks, all of which lack detail on a lot of topics.
For a person on the path to becoming a professional astronomer, there is little point to read introductory general astronomy textbooks, as you essentially have to relearn everything you read in them, later on, because they don't take the approach that a professional astronomer would take. (each substantial article in this Encyc. is written by a qualified subject specialist who is "in on the game" of professional astronomy)
cheers,
Bad Galaxy Man
Anyone needing this encyclopedia should also check out the available copies at
www.abebooks.com