Journey from the Center of the Sun , Jack B. Zirker Princeton U. Press, Princeton, N.J., 2002. $29.95. (302 pp.). ISBN 0-691-05781-8
Journey from the Center of the Sun is written with the experience, perspective, and insight of one who has spent decades in solar physics. Its author, Jack Zirker, graduated in 1996 to astronomer emeritus with the National Solar Observatory at Sacramento Peak, New Mexico. During his career, he contributed to solar physics as observer, experimentalist, theorist, and observatory director. In his own words, “[I] wrote this book because I wanted to share some of my pleasure in the subject. … I wanted to try to explain how the Sun works, the physical principles that govern its behavior, the many things we have learned since Sputnik, and the long list of things we still don’t understand to our satisfaction.” In these objectives he has been abundantly successful.
Solar physics is challenging and provocative because so much observational detail is available and so much remains to be puzzled out. The nearness of the Sun, with its generous photon, particle, and magnetized plasma fluxes, enables discovery of physical details inaccessible from any other astrophysical source. As a magnetically variable star, the Sun yields extravagant observational phenomena that need to be understood and explained from first principles. As Zirker says, “the more information one has, the more complex the phenomenon seems to become.” The very core of the Sun is observable in neutrinos; the interior down to about 0.1 of the solar radius is studied with exquisite precision by helioseismology. Above the photosphere layer (where radiation can escape), the real fun begins: One can observe radiation from gamma-ray to kilometer wavelengths. Outside the magnetosphere of Earth, in situ measurements directly probe the solar wind, solar cosmic rays (energetic charged particles from flares and interplanetary shocks), and magnetized clouds.
Zirker sets out to deal with it all, and does an admirable job. He fits the many pieces together in an eminently satisfying manner. The book is free of mathematics but replete with illuminating cartoon illustrations and minigraphs, which, with only a couple of exceptions, are well integrated into the text. The typography is attractive and readable, with plenty of room in the margin for notes. In this era of brilliantly colored pictures on glossy paper, it was a surprise to open the book and find that, except for an 8-page insert of color plates, all illustrations are in gray scale. Surprisingly few figures suffer from lack of color, and for some of those, the color plates suffice to fill in the missing information. No doubt the use of grayscale figures helped to reduce the cost of the book, and that seems a good tradeoff now that a plethora of beautiful solar illustrations is readily available on the Internet.
It seems to me that this book has two audiences. The great lucidity of explanation and lack of mathematics commend it to the educated lay audience, to undergraduates, and to beginning graduate students. Zirker presents concisely and clearly such basic concepts as thermodynamic equilibrium and the Maxwell-Boltzmann distribution. A daunting challenge to the beginning student (or to anyone seriously interested in solar phenomena) is to master the wealth of significant observational detail and the jargon used by the solar community to describe it. I know of no other source that makes learning this language so pleasant.
The book’s second natural audience is senior astronomers, like me, who have been so occupied with their own niche as to lose track of the great sweep of scientific advance. For them, the book is a pleasant and delightful way to catch up on the field. Zirker names names and comments on personalities (all positively) who have contributed seminally to the science he describes. It is fun to meet old friends as well as new science here. Historical background provides a perspective of how one discovery leads to the next question.
The book is not without its first-edition warts. A few figure references are in error, Ne becomes He in figure 12.3, and some typos creep in. Unfortunately, Zirker tends to use acronyms without spelling them out. This no doubt accounts for the inexcusable use of ISIS for Japan’s Institute of Space and Astronautical Science, the institution that brought us the very successful Yohkoh mission for the study of high-energy solar physics.
At such a reasonable price, Journey from the Center of the Sun should be purchased and read by anyone with an interest in solar astrophysics. One might give it as a gift, as I have done here at Montana State, to every entering graduate student in solar astronomy. I can think of no better toehold in this fascinating but challenging field.
