This revised edition describes our current understanding of the sun -- from its deepest interior, via the layers of the directly observable atmosphere to the solar wind, right out to its farthest extension into interstellar space. It includes a comprehensive account of the history of solar astrophysics, along with an overview of the key instruments throughout the various periods. In contrast to other books on this subject, the choice of material deals even-handedly with the entire scope of important topics covered in solar research. The authors make the advances in our understanding of the sun accessible to students and non-specialists by careful use of relatively simple physical concepts. An incisive, reliable, and well-structured look at all that is fascinating and new in studies of the sun.