BOOK REVIEW

Meilensteine der Astronomie
Von Aristoteles bis Hawking

Jürgen Hamel

Reviewed by Hilmar W. Duerbeck

Published by Franck-Kosmos-Verlags GmbH, Stuttgart, 2006

ISBN 3-440-10179-7, 302 pages, with 24 color and 58 b&w figures, 19.95 EUR

File jad12_8.pdf contains the review in pdf format.

A writer, more specific a writer on the history of astronomy, might from time to time look at the collected document folders with all the research material and reprints, and might wonder has this been all? Especially at a time when recycling is in vogue? And, perhaps with a request or an invitation to submit something, he or she might consider re-using the material before its definitive disposal.

Well, such are my feelings when I looked at Jürgen Hamel's new book Milestones ofAstronomy - From Aristoteles to Hawking. A slight chance for survival of medium-sized publishers like Kosmos is to offer popular books, and a title must attract potential buyers: Aristoteles means the "old'' times, and as concerns the "mad scientist" of modern times, Stephen Hawking has by now dethroned Einstein. In 1998, Hamel had published a Geschichte der Astronomie - Von den Anfängen bis zur Gegenwart (History of astronomy, from the beginnings to the present), which, of course, he could not simply copy. This time, he selected some stones from his research areas - milestones, touchstones, stumbling blocks in the long road of astronomical evolution - and put them between the covers of his new book. So let us look at these (mile)stones.

The reader is informed about Aristoteles on 2 pages, but his medieval interpreter Johannes de Sacrobosco gets 8 pages! Copernicus' life and achievements are described on 9 pages, closely followed by his devotee and translator Rothmann with 8 pages; Copernicus' contemporary, Peter Apian, however, gets about 13! Bessel's and Herschel's lifes and works are described on well-deserved 13 and 15 pages, while the achievements of the two Lucasian professors, Isaac Newton and Stephen Hawking, are just outlined in a single paragraph! Thus, importance is sometimes inversely proportional to text length ...

But let us become serious now. Why should an active historian outline, for the hundreth time, the life of Copernicus, while there are so many interesting, and often neglected, other astronomers? Before the chapter dealing with Aristoteles and other Greek thinkers, the author presents a very good introduction to prehistoric astronomy. Subsequent chapters cover medieval times (Sacrobosco), Copernicus, instruments (Apian), calendars and their makers, telescopes and theological conflicts, women in astronomy and celestial mechanics, "amateur'' astronomers (Herschel and Bessel), philosophy and science (Kant and successors). "At the limits of knowledge'' is the title of the last, somewhat scanty chapter on 20th century astronomy.

The only confusing text is found on p. 43: Die exzentrische Lage der Sphären wurde von Hipparch im 2. Jahrhundert v. Chr. eingeführt. Cum grano salis, this is correct; Hipparchos assumed an eccentric orbit for the Sun. Furthermore, die Erde steht im Mittelpunkt des Deferenten, jedoch um den Betrag der Exzentrizität E vom Mittelpunkt des Exzenters entfernt. A figure showing a deferent circle (and attached epicycle) with center M, and a lower point E called center of world = center of Earth in the caption, tries to illustrate this. The desperate reader does not find the eccenter in the figure, and also does not appreciate why the Earth is in the center of the deferent M when the caption says it is in E. The explanation is that for a planet, having two anomalies, the epicycle does not run on a concentric circle, usually called deferent, but on an eccenter. Thus, in the figure, the circle labelled deferent is the eccenter. In Cellarius' Harmonia Macrocosmica, Table 14, a similar figure explains it all: Eccentricus deferens epicyclum - the eccenter that carries around the epicycle. Since we have switched to Latin, we should mention that on p. 158, we encountered the sentence "in dubia pro res''. Perhaps we are permitted to reply "si tacuisses, philosophus mansisses''.

The reader is cautioned: if this book is used as a road atlas for the history of astronomy, the reader will often find very rough sketches of the progress of astronomy, but from time to time a very detailed map of a very beautiful town or village will be encountered. This well-written and inspiring book can be recommended to everyone who wants to learn about astronomical history somewhat off the beaten track.