The Astronomers' Magic Envelope
An Introduction to Astrophysics Emphasizing General Principles and Orders of Magnitude
Prasenjit Saha and Paul A. Taylor
Working physicists, especially astrophysicists, value `back-of-the-envelope' calculations — short elegant computations or arguments that start from general principles and lead to interesting results. This book guides advanced undergraduates and lower graduates on how to understand astrophysics using general principles and concise calculations.