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THE GENERAL HISTORY OF ASTRONOMY
General editor: Michael Hoskin, University of Cambridge
Volume 2
Planetary astronomy from the Renaissance
to the rise of astrophysics
Part A: Tycho Brahe to Newton
EDITED BY
RENE TATON
Centre Alexandre Koyre. Paris
and
CURTIS WILSON
all manner of books
uas granted by
Henry VIU in IS34.
The University has printed
and published continuously
since 1334.
CAMBRIGE UNIVERSITY PRESS
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© Cambridge University Press 1989
First published 1989
Printed in Great Britain at the University Press, Cambridge
British Library cataloguing in publication data
The General history of astronomy.
Vol. 2: Planetary astronomy from the
Renaissance to the rise of astrophysics.
Pt A: Tycho Brahe to Newton
1. Astronomy to 1950
I. Taton. Rene II. Wilson, Curtis
520'.9
Library of Congress cataloguing in publication data
Planetary astronomy from the Renaissance to the rise of astrophysics
edited by Rene Taton and Curtis Wilson.
P- cm. - (The General history of astronomy; v. 2)
Includes bibliographies.
Contents: pt A. Tycho Brahe to Newton.
ISBN 0 521 24254 1 (pt A)
1. Astronomy - History. 2. Astrophysics - History. I. Taton,
Rene. II. Wilson, Curtis. III. Series.
QB15.G38 1984 vol. 2
520'.9 s-dc!9
[520'.9'03] 88-25817
ISBN 0 521 24254 1
SE
I
CONTENTS
Preface vii Acknowledgements x
I Tycho, Gilbert and Kepler 1 9 The Galilean satellites of Jupiter from
Galileo to Cassini, Romer and Bradley
1 Tycho Brahe Suzanne Debarbat, Observatoire de Paris,
Victor E. Thoren, Indiana University 3 and Curtis Wilson, St John’s College,
Annapolis, Maryland 144
2 The contemporaries of Tycho Brahe
Richard A. Jarrell, Atkinson College, North
III Planetary, lunar and cometary theories
York, Ontario 22
between Kepler and Newton 159
3 The Tychonic and semi-Tychonic world 10 Predictive astronomy in the century after
systems Kepler
Christine Schofield. Bristol 33 Curtis Wilson, St John’s College, Annapolis,
4 Magnetical philosophy and astronomy, Maryland 161
1600-1650 11 The Cartesian vortex theory
Stephen Pumfrey, University of Lancaster 45 Eric J. Alton, Oldham, Lancashire 207
5 Johannes Kepler 12 Magnetical philosophy and astronomy
Owen Gingerich, Harvard-Smithsonian from Wilkins to Hooke
Center for Astrophysics 54 J. A. Bennett. Whipple Museum of the
History of Science, Cambridge University 222
II The impact of the telescope 79
IV The Newtonian achievement in
astronomy 231
6 Galileo, telescopic astronomy, and the
Copernican system 13 The Newtonian achievement in
Albert Van Helden, Rice University, astronomy
Houston, Texas 81 Curtis Wilson, St John's College, Annapolis.
Maryland 233
7 The telescope and cosmic dimensions
Albert Van Helden, Rice University, A glossary of technical terms
Houston, Texas 106 Curtis Wilson, St John’s College, Annapolis,
8 Selenography in the seventeenth century Maryland Gi
Ewen A. Whitaker, Lunar and Planetary Illustrations: acknowledgements and sources Ai
Laboratory, University of Arizona 119 Index li
THE CONTENTS OF PART B OF VOLUME 2 ARE:
V Early phases in the reception of Newton’s 23 The transits of Venus and the dimensions
theory of the solar system
14 Vortex theory in competition with 24 The discovery of Uranus. Bode’s law, and
Newtonian celestial dynamics the asteroids
15 The shape of the Earth 25 Gauss and the determination of orbits
16 Clairaut’s derivation of the motion of the 26 The introduction of statistical methods
lunar apse into astronomy
17 The precession of the equinoxes from 27 From the method of averages to the
Newton to d'Alembert and Euler method of least squares
18 The solar tables of Lacaille and the lunar
tables of Mayer VIII The development of theory during the
nineteenth century
19 Clairaut and the return of Halley’s comet
in 1759 28 The golden age of celestial mechanics:
from Laplace to Poincare
VI Celestial mechanics during the eighteenth
century IX The application of celestial mechanics to
the solar system to the end of the
20 Pre-Lagrangian efforts: Maclaurin. nineteenth century
Clairaut. Euler, and d'Alembert
29 Numerical integration applied to orbits
21 The work of Lagrange
30 Lunar and planetary ephemerides from
22 Laplace and the Me'canique celeste Picard to Newcomb
31 The development of satellite ephemerides
VII Observational astronomy and the during the eighteenth and nineteenth
application of theory in the late centuries
eighteenth and early nineteenth centuries
PREFACE
Volume 2 of The General History of Astronomy deals place on 24 August of that year. Tycho’s response,
with the history of the descriptive and theoretical over the remaining years of the century, was to
astronomy of the solar system, from the late six give to the accumulation of accurate astronomical
teenth century to the end of the nineteenth observations a priority and importance it had never
century. had before. The store of observations he accumu
In the European tradition from the time of Plato lated in the process became the empirical basis for
to the sixteenth century, theoretical astronomy Kepler’s justly titled Astronomia nova (New Astron
viewed its task as the reduction of the apparent omy), which made possible a new level of accuracy
celestial movements to combinations of uniform in the prediction of planetary motions.
circular motions. This formulation was still axiom Inextricably bound up in Kepler’s theory was a
atic for Copernicus; indeed, Ptolemy’s violation of new celestial physics, founded on the Copernican
the axiom in his Almagest was an important stimu vision of the solar system. It was an attempt to
lus leading Copernicus to undertake his renovation account for the observed motions by means of
of astronomy. To many astronomers working in hypothesized quasi-magnetic forces and struc
■ the later sixteenth century, after the publication of tures. Kepler did not and could not derive his ‘laws’
Copernicus’s De revolutionibus (1543), the major of planetary motion - elliptical orbit and areal rule
achievement of this work was that it had freed - from observations alone; on the contrary, his
astronomy from such violations of principle; in analysis of Tycho's observations was directed by
contrast, the associated rearrangement of circles his own highly conjectural celestial physics. Conse
that put the Sun at the centre and attributed mo quently, his contemporaries and successors could
tion to the Earth was, in the view of many, an not but find the hypothetical foundations dubious.
absurd error. Copernicus’s work, both in its adher Yet the new predicative accuracy that Kepler
ence to the long-held axiom of uniform circular achieved was too remarkable to be ignored. As
motion and in its organization, was thoroughly tronomers were ineluctably faced with a challenge:
traditional; and it is thus fitting that Volume 1 of to achieve results as successful as Kepler’s, but with
The General History of Astronomy, which is devoted more convincing physical foundations. It is not
to the history of ancient and medieval astronomy, easy to imagine what the history would have been
should conclude with it. But, as all the world if Kepler's Astronomia nova had never appeared to
knows, the Copernican rearrangement contained pose this problem. At least we can say: exceedingly
the seeds of a further transformation. different.
The story of that transformation begins with the The seventeenth century was a period of com
work of the Danish astronomer Tycho Brahe, plex transition in thought, belief, and knowledge of
which is also the starting-point for Volume 2. In the world; delineation of the aspects of the transi
1563 young Tycho, then a student at Leipzig, was tion that bear on astronomy is a major concern in
shocked to discover that the accepted astronomical Part A of Volume 2. From 1610 onward, telescopic
tables of the day (the Alfonsine based on Ptolemaic observations of the heavens revealed new facts that
theory, and the Prutenic based on Copernican had to be incorporated in the system of the world,
theory) were, both of them, days out in predicting whether this was conceived to be geocentric or
the conjunction of Jupiter and Saturn that took heliocentric. Studies of refraction and parallax
Preface
viii
showed the Earth to be some 18 times further from its constituent bodies. By the end of the century
the Sun than had previously been believed, and so Simon Newcomb and his collaborators would
nearly 6000 times smaller in relation to the volume achieve a precision in their prediction of planetary
of the Sun. New studies of motion and force, of motions measured in seconds or fractions of a sec
falling bodies and the impacts of bodies, were pro ond of arc. Yet some inconsistencies remained,
posed by Galileo, Descartes, and others, a major among them an anomalous motion of the node of
motive being to show that the heliocentric system Venus and an anomalous motion of the perihelion
was not incompatible with physical principle. The of Mercury. The first of these was a statistical arti
Keplerian planetary tables were tested repeatedly, fact; the second would become evidence for a new
and continued to prove superior to earlier tables. theory of gravitation, which would supersede that
An impressively persuasive replacement for of Newtonian physics.
Kepler’s celestial physics was at length provided in The scope of Volume 2 does not include general
1687 by Isaac Newton's Principia. Part A of Vol relativity. Nor does it embrace astrophysics, which
ume 2 concludes with the story of its emergence, came into being in the 18 50s with the development
and a summary of the astronomical results that by Kirchhoff and Bunsen of spectral analysis. Both
Newton succeeded in deriving from his principle of topics belong to Volume 4, Astrophysics and Twenti
universal gravitation. eth-century Astronomy to 1950. Similarly excluded
Part B. after a section devoted to the gradual from the scope of Volume 2 are the topics of stellar
acceptance of the Newtonian doctrine during the astronomy and cosmology, and astronomical in
first half of the eighteenth century, takes up the struments, institutions and education, from the
history of the efforts, from the 1740s onward, to Renaissance to the beginnings of astrophysics:
deduce detailed mathematical consequences from these topics constitute the subject-matter of Vol
universal gravitation. It is the story of what the ume 3. At certain points the concerns of Volumes 2
eighteenth century called ‘physical astronomy’, and 3 overlap. Tycho’s sighting instruments were
but what Laplace in 1799 renamed ‘mecanique highly relevant to his observational achievement;
celeste', celestial mechanics. The challenge of de and from the 1660s and 1670s onward, the pendu
ducing the consequences triggered the develop lum clock, telescopic sights, and the filar microme
ment of new forms of mathematics. Of notable ter were similarly relevant to the programmes for
importance here were the trigonometric series, first the improvement of lunar and planetary tables that
introduced by Euler, but with later contributions were adopted by the newly founded Paris Observa
from d'Alembert, Clairaut, Lagrange, and Laplace; tory and Greenwich Observatory. Again, Bradley’s
a new mechanics of the rotation of rigid bodies, to discoveries of the aberration of light and nutation
which d'Alembert and Euler were the chief initial were prerequisites for the attainment of seconds-of-
contributors: and the method of variation of the arc accuracy in the prediction of planetary and
constants of integration in the solution of differen lunar positions. For these and similar topics con
tial equations, developed by Euler, Lagrange, and cerned with the stars and with observational in
Laplace. The story also involves the introduction of struments and their institutional context the
statistical calculations into astronomy: at first, reader must be referred to Volume 3.
with a less than satisfactory outcome, by Euler: Our aim in Volume 2, as in the other volumes of
then more successfully by Tobias Mayer, whose the series, has been to throw light on the develop
example was followed by Laplace. With Laplace ment of astronomy as an inventive human activity.
and Gauss the use of statistical procedures in bring We have sought to view the questions and prob
ing multiple data to bear on the determination of lems of the astronomers of a given time in the very
astronomical constants became de rigueur. way in which those astronomers saw them, with
Through the nineteenth century the grand theo out regard for what has later come to be accepted as
retical questions remained those that Laplace had ‘correct’. We have not attempted an encyclopaedic
forcefully posed and prematurely claimed to an completeness of coverage: rather, our goal has
swer: the question of the stability of the solar sys been to provide an intelligible account of the major
tem. and the question of the adequacy of universal endeavours through which astronomy has
gravitation to account for the observed motions of evolved.
Preface ix
A word is in order with respect to the division of Finally, I have the grateful duty of acknowledg
tasks between the two editors of Volume 2. Rene ing the extensive guidance and generous assis
Taton and myself. Professor Taton resigned his tance provided a neophyte editor by the General
editorship in 1983. By this time he had drawn up Editor of the series, Michael Hoskin. He has again
the general plan of the volume, and had engaged and again given generously of his time, knowledge,
authors to write rather more than half of the sec and thought to the solution of the problems and
tions envisaged. The engaging of authors for the difficulties, whether major or minor, encountered
remaining sections has been my responsibility, and in the assembling and editing of this volume. Our
I have also undertaken some reorganization of undertaking has been, in every aspect, a joint
materials, reducing the original tripartite scheme endeavour.
to a two-part plan, and introducing into Part B a
number of new sections which focus on the appli
cation of theory to observation. Annapolis, Maryland Curtis Wilson
ACKNOWLEDGEMENTS
Albert Van Helden, Chapters 6 and 7, is grateful for abouts of the large la Hire drawing of the Moon.
comments received from Owen Gingerich and Olaf S. Debarbat and Curtis Wilson, Chapter 9, are
Pedersen. grateful for the contributions and discussions at the
Ewen Whitaker, Chapter 8, thanks the following Table Ronde du CNRS held in Paris in June 19 76 on
individuals and institutions for kindly supplying, “Roemer et la vitesse de la lumiere”.
gratis, negatives of lunar images and maps: 0. Van Curtis Wilson, Chapters 10 and 13, is grateful to
de Vyver, SJ, Henri Michel (Societe Beige the Program for History and Philosophy of Science
d’Astronomie and the Cabinet des Estampes, Biblio- of the US National Science Foundation for support
theque Nationale, Brussels), A. Orte (Observatorio of his research on the history of lunar and plan
de Marina, San Fernando), the Astronomer Royal etary astronomy in the seventeenth century after
for Scotland (Royal Observatory, Edinburgh), and Kepler. An earlier version of the first part of Chapter
F. Warren Roberts (Sid W. Richardson History of 13 was published in The Great Mens Today for 1985
Science Collection, Humanities Research Center, (Encyclopaedia Britannica, 1985) under the title
University of Texas at Austin). He also thanks the “Newton’s path to the Principia". To D.T.
following for placing their collections at his dis Whiteside, for extensive and painstaking criticisms
posal: the Earl of Egrement and Leconfield, the and suggestions regarding both chapters, his in
Royal Greenwich Observatory, the Royal Astro debtedness is immense. I. Bernard Cohen and R.S.
nomical Society, and 1’Observatoire de Paris. Fi Westfall read a near-final version of Chapter 13
nally, he thanks Godfrey Sill for translating the and so made possible the elimination of a number of
entire text and quotations from Van Langren’s erroneous or misleading formulations. For the in
map, excerpts from which were used in the text, terpretations finally adopted, however, the author
and Micheline van Biesbroeck Wilson for obtaining alone is responsible.
data, while visiting Paris, regarding the where
PART I
Tycho, Gilbert and Kepler
