Reading this exemplary treatise on the sun, one has the feeling that Harvard astronomer Noyes is both teacher and student. He knows what he wants to tell and he also knows the sticking points. ""Where does the solar surface stop,"" he may ask, ""and its atmosphere begin?"" ""That is not a simple question. The Sun has no surface. . . . We cannot even in imagination stand on the surface of the Sun, for it would offer no resistance to our falling rapidly into the depths."" Then comes a density explanation as to why that fuzzy non-surface appears as a sharp edge when you look at the sun in natural light. This patience and logic allows Noyes to lead the reader on a majestic tour of the sun from outside in, from its birth 5 billion years ago to its ultimate destiny as a white dwarf dying star. The tools of the trade--solar telescopes, spectroscopes, orbiting vantage points--are explained in turn, and those who have but a nodding acquaintance with phrases like Balmer series or Zeeman Effect may, to their delight, understand what they're all about. In addition to chapters probing the sun's chemistry, its nuclear furnace, the magnetic fields that underlie sunspot activity (and other sun-centered affairs), Noyes also deals with practical earthly matters in chapters on solar energy and the sun's effects on climate. (Variations in the solar constant, solar winds, and ultraviolet radiation have all been implicated in Earth weather, but the evidence is far from firm.) No Sagan melodramatics or Asimov earthiness--but Noyes' sunny straightforwardness makes this a fine source book for interested adults and an excellent introductory text for budding astrophysicists.