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On Sunspots

Translated and with an Introduction by Eileen Reeves and Albert Van Helden

Galileo’s telescopic discoveries, and especially his observation of sunspots, caused great debate in an age when the heavens were thought to be perfect and unchanging. Christoph Scheiner, a Jesuit mathematician, argued that sunspots were planets or moons crossing in front of the Sun. Galileo, on the other hand, countered that the spots were on or near the surface of the Sun itself, and he supported his position with a series of meticulous observations and mathematical demonstrations that eventually convinced even his rival.


On Sunspots collects the correspondence that constituted the public debate, including the first English translation of Scheiner’s two tracts as well as Galileo’s three letters, which have previously appeared only in abridged form. In addition, Albert Van Helden and Eileen Reeves have supplemented the correspondence with lengthy introductions, extensive notes, and a bibliography. The result will become the standard work on the subject, essential for students and historians of astronomy, the telescope, and early modern Catholicism.

432 pages | 108 halftones, 2 line drawings | 6 x 9 | © 2010

History of Science

Physical Sciences: Astronomy and Astrophysics, Physics and Astronomy


“[This volume] will be essential to historians interested in the development and use of the telescope and in religion of that period. Highly recommended.”

M. K. Hemenway | Choice

“This is an excellent addition to the literature on Galileo and, more generally, on the Copernican Revolution. It makes available important works that are relatively inaccessible in their original edition and have never been fully translated into English.”

Maurice Finocchiaro, University of Nevada, Las Vegas

“This translation is both timely and commendable. Until now, English-speaking students of Galileo and Scheiner have been poorly served. For the first time, readers have access to both sides of this important debate in the same language. This will be an essential text.”

Nick Wilding, Georgia State University

Table of Contents

List of abbreviations

1 Introduction
2 Sunspots before the telescope
3 Turning the telescope to the Sun: Th omas Harriot and Johannes and David Fabricius
4 Christoph Scheiner
5 Tres Epistolae
6 Galileo answers Apelles
7 Galileo’s fi rst letter
8 Galileo’s second letter
9 A more accurate inquiry from Ingolstadt
10 Accuratior Disquisitio
11 Galileo responds and goes into print
12 Galileo’s third letter
13 Rematch, 1630–1632

1. Scheiner and Galileo on the nature of the Moon
2. Galileo to Maff eo Cardinal Barberini
3. Carlo Cardinal Conti to Galileo on Scripture
4. Scheiner’s calculation of the transit of Venus
5. Galileo’s demonstrations
6. Front matter of Istoria e dimostrazioni intorno alle macchie solari e loro accidenti



Italian Ministry of Foreign Affairs: Translation Prize

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