Extravaganza with a star-studded past

The Cambridge Illustrated History of Astronomy

March 14, 1997

There have always been astronomers. Every culture that anthropologists have come across has had its ideas about those mysterious lights in the sky. The story that connects this early fascination with the heavens to the highly developed science of astronomy we know today, complete with subdivisions like astrophysics and cosmology, is a long one. This book will probably become the standard one-volume version of the tale.

Telling the story of these millennia of observation and theory involves a massive act of compression. Nobody knows this better than Michael Hoskin, founder of the excellent Journal for the History of Astronomy and general editor of the General History of Astronomy, also published by Cambridge University Press. Here, minor characters are omitted - Jeremiah Horrocks does not rate a mention - to make room for lengthy treatment of deserving subjects. Fascinating "might-have-beens", such as Galileo's observation of Neptune, suffer the same fate, although the story of Neptune's eventual discovery is told in detail.

One constant of the resulting story is that despite its intangible subject matter, astronomy is a valuable applied science. People who do not know when to plant crops might starve, while people who cannot determine latitude and longitude might be shipwrecked - and often have been. And there is the calendar, which Hoskin regards as the basic requirement society has of astronomers.

Now that these problems have essentially been sorted out, astronomy has a curious dual role, of which the first part is the satisfaction of wonder. The public response to the spectacular pictures from the Hubble Space Telescope leaves no doubt that modern astronomy interests and awes many people who do not think of themselves as science enthusiasts.

In addition, since the era when it was the only science with its own muse, Urania, astronomy has become one science among many. It is enriched by links to mathematics, physics, the earth sciences and other subjects, including engineering if one counts the telescopes, satellites and charge-coupled devices with which astronomers gather their data.

The core of any history of astronomy is the tale, from Babylon and Greece to Copernicus, Tycho and Kepler, of the realisation of the shape of the solar system, the subsidiary position of the earth and the free movement of the planets in space. This is told excellently by Hoskin and Owen Gingerich, although here and throughout the book, picture researcher Callie Kendall also deserves a round of applause for the volume's fabulous images. But readers will also be grateful for the Cambridge Illustrated History's coverage of less well-trodden ground. Notable is Clive Ruggles and Hoskin's work on prehistoric astronomy. Despite the role of the Journal for the History of Astronomy in building up archaeoastronomy as a subject, the chapter here takes a sceptical view of the possibility that major stone circles were used as astronomical calculators.

Also valuable is the book's look at Islamic astronomy, if only for helping to dispel the notion that Muslims did little more than store the astronomical knowledge of the Greeks for rediscovery by Europeans some centuries later. Islam has many uses for astronomy, including timing the start of the lunar month, knowing the direction of Mecca (now a handy source of business for electronics gadget-makers) and telling the faithful the correct times for prayer. This last problem involved solving problems in geometry with the help of Greek and Indian mathematics and Muslim-developed solutions.

In addition, Muslim astronomers had some of the world's most sophisticated observatories and instruments, notably Ulugh Beg's observatory at Samarkand. And the role of mosque time-keeper allowed astronomers to have professional posts that would have been impossible in Europe.

Like Christianity, Islam has always been hostile to the idea that the sky exerts direct influence on our destinies, condemning astrology and sometimes persecuting astrologers, a practice that might usefully be revived today in nonviolent form. Muslim observers had to cope with many accusations of interfering with the natural course of events. One observatory was destroyed after being held responsible for various deaths and defeats in battle, while a luckless astronomer was killed for "crimes including communication with Saturn". Just why people persist in believing in such celestial influences on their lives is a perennial question which this book raises in many ways.

Smaller-scale contributions to the History will also grip the reader. Astrolabes look nice, but just how did anyone use them? The answer, as told here in four pages, is fascinating and will increase anyone's respect for the ingenuity of their makers. Likewise, much has been made of the problem of finding longitude at sea: but discovering latitude is by no means a trivial issue, and how it was done makes an engaging read.

In the post-Kepler world, the History scores again by giving adequate space to William Herschel, now best known as the discoverer of Uranus. His real significance, well explained here, is that he was the first person to appreciate deep space as a dynamic place that scientists could understand, not a backdrop against which planets moved. Before he came along, astronomers had stopped thinking that the stars were lights stuck to a crystal sphere, but had not acted on the idea.

Herschel found Uranus, and made many other discoveries, by building the biggest telescopes he could - a significant feat of technology - and using them tirelessly. His son, John, who also observed from the southern hemisphere, is described as the last person to view the whole sky through a powerful telescope, before astronomical specialisation took over.

Entering the modern era, the History thoughtfully covers topics such as the growth of astronomy as a subject, with the formation of learned societies, the foundation of laboratories and the launch of journals. And the rise of astrophysics, which allows the composition and condition of material at the edge of the observable universe to be determined in detail, is told well by Hoskin and David Dewhirst. Although there are still unresolved issues about the size of the universe, developments this century have allowed distances to the galaxies to be determined and the dynamics of galactic clusters to be unravelled, only 150 years after the spiral structure of galaxies was first determined by William Parsons in Ireland.

If there are reservations about this generally excellent book, they arise at the end of the story. The discovery of the cosmic background radiation is covered well, but the material on quasars is slight and active galactic nuclei do not get a mention. And the baffling world of superstrings, symmetry and neutrino astronomy passes the authors by.

Readers might also regard the book's treatment of astronomy's expansion into orbit and into deep space as inadequate. The quick mention of a few space missions and orbiting observatories, and a paragraph on the Hubble Space Telescope, are an inadequate reflection of the revolution these instruments have allowed. And missing the chance to use a few Hubble images and space probe shots of the planets was a mistake.

Martin Ince is deputy editor, The THES.

The Cambridge Illustrated History of Astronomy

Editor - Michael Hoskin
ISBN - 0 521 41158 0
Publisher - Cambridge University Press
Price - £24.95
Pages - 392

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