Cover image for The sun in the Church : cathedrals as solar observatories
The sun in the Church : cathedrals as solar observatories
Heilbron, J. L.
Personal Author:
Publication Information:
Cambridge, Mass. : Harvard University Press, 1999.
Physical Description:
ix, 366 pages : illustrations (some color) ; 26 cm
Format :


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Material Type
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QB29 .H33 1999 Adult Non-Fiction Non-Fiction Area

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Between 1650 and 1750, four Catholic churches were the best solar observatories in the world. Built to fix an unquestionable date for Easter, they also housed instruments that threw light on the disputed geometry of the solar system, and so within sight of the alter, subverted church doctrine about the order of the universe.

Reviews 2

Library Journal Review

It is difficult for contemporary readers who live in an increasingly global world to comprehend the difficulty of establishing the correct date of EasterÄthe first Sunday, after the first full moon, after the vernal equinox. Heilbron (formerly history and vice chancellor, Berkeley; currently Senior Research Fellow, Oxford) chronicles the ironic relationship between astronomy and the Catholic Church as it seeks the means to determine this date. This is the story of politically astute astronomers and cardinals who have to reconcile church doctrine with Galileo's universe. Heilbron deals specifically with four cathedrals, which, as a result of the "Easter date problem," function as both houses of worship and excellent solar observatories. The text is filled with fine detail and is richly illustrated. An erudite and scholarly work with extensive notes and bibliography, this may be a bit narrow in scope for the average reader; recommended for large public and academic libraries.ÄJames Olson, Northeastern Illinois Univ. Lib., Chicago (c) Copyright 2010. Library Journals LLC, a wholly owned subsidiary of Media Source, Inc. No redistribution permitted.

Choice Review

The spectacle of the image of the sun projected on meridian lines in several of the great Italian cathedrals is captured in the beautiful color plates highlighting this book. But Heilbron (Univ. of California, Berkeley; Oxford Univ.) intimates that the lines were more than works of art; they were tools created and used by astronomers to sort out the problem of maintaining the correspondence between religious events and a calendar that was based on the position of the sun and moon. This excellent book explains the difficulty posed by the inconvenient lengths of the lunar month and solar year, and discusses how observations of the solar image crossing a precisely aligned mark could solve the problem. It was with caution that the Catholic Church supported this research, since the interpretation of the changing position of the sun inevitably required a theory of the motion of the earth about sun, and the Church had condemned Galileo and his ideas. The story of the construction of the meridian lines in the 16th and 17th centuries is presented in detail, with the more technical description of the geometrical basis of meridian lines relegated to the appendixes. The book is well written, though demanding of the reader. General readers; undergraduates through professionals. D. E. Hogg; National Radio Astronomy Observatory

Table of Contents

Acknowledgmentsp. IX
Introductionp. 3
Renaissance and Astronomyp. 5
Counter-Reformation and Cosmologyp. 12
Wider Uses of Meridianep. 21
1. The Science of Easterp. 24
The Luminaries and the Calendarp. 25
A Scandal in the Churchp. 36
2. A Sosigenes and His Caesarsp. 47
Florencep. 47
Bolognap. 68
Romep. 77
3. Bononia Docetp. 82
A New Oracle of Apollop. 82
Astronomia Reformatap. 101
4. Normal Sciencep. 120
Perfecting the Parametersp. 123
Repairs and Improvementsp. 137
5. The Pope's Gnomonp. 144
Calendrical and Other Politicsp. 144
The Meridian in Michelangelo's Churchp. 155
Meridiane and Meridiansp. 166
6. The Accommodation of Copernicusp. 176
Heliometers and Heliocentrismp. 176
Protective Measuresp. 187
Book Banningp. 197
7. The Last Cathedral Observatoriesp. 219
The Things Themselvesp. 219
Their Resultsp. 234
Their Competitorsp. 246
8. Time Tellingp. 265
Some Means of Conversionp. 266
The Equation of Timep. 275
More Light Playp. 284
Appendicesp. 293
Abbreviationsp. 303
Works Citedp. 305
Notesp. 329
Creditsp. 355
Indexp. 357