Looking at dwarfs and cool red giants

Henry Norris Russell was widely referred to as "the Dean of American Astronomers" - hence the title of this new book - but others called him "the General". The importance of his contributions to astronomy, not only in the United States but over the entire scientific world, can hardly be overestimated. His career spanned a large part of the 20th century, during which the whole of our astronomical outlook was revolutionised. His contemporaries included men of the stature of Edwin Hubble, Edward Charles Pickering, Harlow Shapley and George Ellery Hale, but as an all-rounder it is probably true to say that Russell surpassed them all. He died more than 40 years ago, in February 1957, just before the start of the space age, so this first full-length biography of him is long overdue.

David DeVorkin is well qualified to undertake the task. He is curator of the Smithsonian's National Air and Space Museum and a former chairman of the history division of the American Astronomical Society. It is clear that a tremendous amount of research has gone into the preparation of this biography, and the result is an unqualified success.

Russell will always be associated with the famous H-R or Hertzsprung-Russell diagram, originally known simply as the Russell diagram; it was first drawn by the Danish astronomer Ejner Hertzsprung, but Russell extended it and gave its first interpretation. It links the real luminosities of the stars with their surface temperatures, and originally was thought to indicate a definite evolutionary sequence; in Russell's first theory a star began its life as a large, cool red giant, heated to become a hot bluish white star, and then faded back to become a dim red dwarf before losing the last of its light and heat. This proved to be wrong: red giants are not youthful. They are in fact well advanced in their evolution, but the theory provided a basis for all future work. In this, Russell played a very major role, and his research also extended to other branches of astronomy, such as the problems of the origin of the solar system. His knowledge of the entire astronomical field was encyclopedic, and probably unmatched by any of his contemporaries.

Yet of equal, perhaps even greater importance was the way in which he marshalled all branches of research and combined them. As a teacher, he produced many worthy successors, and there were few leading astronomers of the latter part of the 20th century who did not owe him a great deal. For many years his influence and authority remained unrivalled.

This is not to say that he did not have human failings. He could be slow to change his mind and to abandon old ideas, even in the face of mounting evidence, and he could be influenced by the personalities involved: for example, it was with great reluctance that he finally abandoned the old theory, championed by Harlow Shapley, that the objects we know to be galaxies were indeed independent systems rather than minor features of our own Milky Way. Neither did he avoid becoming involved in some of the disagreements and controversies of the time, even when these became acrimonious. DeVorkin's handling of these disputes is admirably fair and balanced - and here I am in a good position to judge, because I knew most of the main characters involved. It cannot honestly be said that Russell was a successful observatory director; it simply was not his forte. One very strong point about DeVorkin's book is that Russell's shortcomings are neither exaggerated nor glossed over.

As well as giving a very detailed account of Russell's life and work, the book also paints an excellent picture of the progress of astronomy between the time when Russell began his career, at the turn of the century, and ended it 50 years later. The whole scene had been transformed, and Russell's part in this is well brought out.

In some ways he lacked charisma. His rather austere religious upbringing, his formality and his occasional bursts of temper were characteristic of him: he did not often make close friendships, and it may be fair to say that a sense of humour was not his strongest point. But of his brilliance, his integrity, his overall grasp and, perhaps above all, his enthusiasm there can be no doubt at all. He was also an expert populariser of astronomy, and his articles in Scientific American are still remembered. With R. A. Dugan and J. Q. Stewart he produced a classic textbook of astronomy, which remained the standard for many years.

Another strong point about this book is that it has an extensive and very well-researched list of references, which will be of great value to future students. The text itself is beautifully written, and the illustrations are adequate. Errors and omissions are conspicuous only by their absence.

It would be difficult to make any adverse criticisms of the book. As one of the most important astronomers of the 20th century, Russell deserves a first-class biography. DeVorkin has provided it.

Patrick Moore is the author of more than 60 books, mainly on astronomy. His latest is the Astronomy Data Book .