More or less hot off the press, John & Mary Gribbin's 'From Here to Infinity', published by The Royal Observatory in 2008. Here is a guide to Astronomy that is a nice size,(almost a pocket book) yet is packed with superb colour photographs and artist impressions of stellar objects. Each chapter is concise and up to date covering The Earth, Moon, Sun, Inner and Outer Solar System, Stars, Milky Way and Other Galaxies, Cosmology and Life in the Universe.
I don't think it matters at what level the reader enters this Guide, there is certainly something for every reader, and can be recommended for all ages. If I wish to be pedantic, I would wish a Royal Observatory Guide to Astronomy to refer to the constellation of Ursa Major as 'The Plough', (ye Olde Anglo Saxon) and not 'The Big Dipper', which is some 19th century term slapped onto the great bear that originates from 'ahem' overseas.