Astrophysics is a subject that is often - with some justification - regarded as extremely difficult, requiring at least degree-level mathematics as a prerequisite to its understanding. Consequently, many amateur astronomers just don't bother, and miss out on the fascinating fundamentals of the subject, and often on an understanding of exactly what they are observing.
Mike Inglis' quantitative approach to astrophysics cuts through all the incomprehensible mathematics, and explains all aspects of astrophysics in simple terms.
A unique feature of this book is the way that example objects for practical observation are given at every stage, so that practical astronomers can go and look at the objected or objects under discussion, using only commercial amateur equipment.