First light of the newborns

The Birth of Stars and Planets

一月 5, 2007

Patrick Moore is impressed by a history of the Universe in its infancy

This book gives the immediate impression of being beautifully produced and printed. The photographs, many of them taken with the world's most powerful telescopes - including, of course, the Hubble Space - are reproduced as well as I have ever seen in a book of this kind, and the pictures of equipment are equally good. The selection of images cannot be faulted, and the print is admirably clear.

But this is much more than a coffee-table book. It is in places decidedly technical, having been written by two distinguished astronomers: John Bally, a professor at the University of California, and Bo Reipurth, who carried out his research at the University of Hawaii before moving to the European Southern Observatory in Chile; after a spell at the University of Colorado, he returned to the University of Hawaii. Both authors have made notable contributions to astrophysics and would be expected to write an outstanding book. They have done so - nearly.

The evolution of stars and planetary systems is a complicated subject, and many books about it are either too elementary or too advanced. Bally and Reipurth have tried to avoid falling into either of these traps, and in the main they have succeeded. There are virtually no mathematical formulae, and the text can be followed by any reader with a smattering of scientific knowledge. There is also a lengthy appendix in which the most important parts of each chapter are summarised. Having finished reading the text, many non-specialists will read through the appendix and then turn back to re-check the relevant sections of the main book. This is an excellent system, and other authors would be well advised to adopt it.

The first three chapters provide a general introduction to what we have found out about the universe as a whole. All our ideas have changed over the past decade or two; we are modestly confident in claiming that everything - space, time, matter - came into existence with the big bang, now dated 13.7 thousand million years ago. (Note that billion is used in the US sense: one thousand million.) Ground-based instruments are then discussed, and space research methods are introduced. It is sometimes easy to forget that the space age began a mere half-century ago, with the ascent of Russia's first artificial satellite. Then we come to consider the very first stars, and here the authors do not pretend that our knowledge is complete. We cannot look back to the moment of creation and we do not have a full understanding of "how" or "why" the big bang happened.

From the time the first stars began to shine, the story is much less incomplete, and Bally and Reipurth tell it admirably. We begin with the ancient "cold universe", when newborn stars are surrounded by cocoons of obscuring material, so that we depend mainly on observations made at infrared wavelengths; only later did it become possible to rely on visible light.

The authors take care to make sure that the newcomer to astronomy is not "lost", while at the same time giving enough data to be useful to the really serious reader. This leads on to descriptions of the later stages of stellar evolution, and to the formation of open and globular clusters; one chapter is titled "Chaos in the nest: The brief lives of massive stars", and we may reflect that we are lucky in that the Earth moves round a star that is much more sedate. Not all authorities are in agreement about the birth of the Earth and the other members of the solar system, and up to now we have had only limited information about planets of other stars, though there is absolutely no reason to believe that the Sun's family is unique or even unusual.

As well as photographs, the book contains excellent artists' impressions, such as the spectacular painting of the formation of a planetesimal.

Collisions between galaxies are dealt with in some detail - after all, we are sure that there will be an eventual collision between our Milky Way and the Andromeda Spiral, which is racing towards us even though it is almost 3 million light-years away. The penultimate chapter of the main text returns to the time of the earliest stars and galaxies, with an account of the all-important cosmic microwave background. Finally, and inevitably, we ask whether there can be other life forms in the cosmos - and, if so, have we any hope of contacting them?

All this is most impressive. The reader who follows the text through will be left with an excellent picture of the early history of the Universe, so far as we know it. A book of this scope is completely different from any book that could have been written as recently as, say, 1990; astronomy used to be regarded as a static science, but now it is so fast-moving that each year, or even each month, brings its quota of new discoveries and new theories. Bally and Reipurth have taken this into account and their text is fully up to date at the time of publication. They write with great authority, and it is notable that they have been able to include some of the results of their own work.

It may seem churlish to make any real criticism of so handsome and comprehensive a book, but there are two aspects that should be borne in mind during the preparation of the next edition.

The first is that the proofreading is sloppy. Names have been misspelt; for instance "Clark" instead of "Clerk" and the British astronomer Sir James Jeans becomes "James Jean", and we learn that "the Jean's mass depends only on the cloud density and cloud temperature". There are various other slips that are admittedly minor but nevertheless irritating, and should be weeded out. There are also factual mistakes. The worst is the description of the supernova of 1054, whose remnant we now see as the Crab Nebula, which, according to the authors, "became almost as brilliant as the Moon". It may have easily surpassed Venus, and was visible with the naked eye in broad daylight, but to compare it with even the quarter-Moon is absurd; it was not nearly as bright as the 1006 supernova, in Lupus, which admittedly was not so well-documented. And it is somewhat misleading to say that "star formation has stopped in the Orion Nebula"; this statement would be challenged by many astrophysicists.

This leads to the second, and more serious criticism; the book needs the attention of a skilled sub-editor. In places the English is strange, and cases of faulty grammar are to be found on many pages. Split infinitives do not really matter, but very often the style obscures the real meaning.

Readers may, for instance, be puzzled by the reference to "nuclear star clusters". This refers to star clusters lying near the centre of a galaxy, not to any nuclear power. And can Sagittarius A-star, marking the centre of our own Galaxy, be accurately described as "a faint radio star"? Throughout, the text reads like a translation - Jand given that one of the authors is Danish, a reader is bound to wonder whether or not the original draft was written in English.

It would be wrong to make too much of this. Even as it stands the book is very useful as well as attractive, and is well worth including in any astronomical library, amateur or professional. All in all - a very good book, but it could have been even better.

Sir Patrick Moore is the author of more than 60 books, mainly on astronomy.

The Birth of Stars and Planets

Author - John Bally and Bo Reipurth
Publisher - Cambridge University Press
Pages - 306
Price - £25.00
ISBN - 0521801052

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