A bridge between introductory and advanced technical treatments, this readable and authoritative translation from the French provides an excellent guide to observational astrophysics. Physics students and professionals will appreciate the text's mid-level approach, in which methods of research and observation receive as much attention as results.Confining his discussion to normal stars, the author examines current methods of stellar photometry and spectroscopy and the main results of research involving star classification and properties. Additional topics include construction of Hertzsprung-Russell diagrams, Yerkes two-dimensional classification, masses and densities of stars, general theories about the constitution of stellar atmospheres and the evolution of stars, and much more. Indispensable for specialists, this volume is also a fine resource for hobbyists and others with some grounding in astronomy wishing to further explore the intricacies of astrophysics.