The Sun in the Church: Cathedrals As Solar Observatories

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Summary: I wish there were more books like this!
Review: I'm a professor of mathematics, but I'm also a "closet historian". This book is a great work of scholarship both in terms of history and mathematics. It's true that if you don't know much about spherical astronomy, you may get a bit of shell-shock, but why don't you pick up Kaler: "The Ever-changing Sky" or Evans: "The History and Practice of Ancient Astronomy" to learn the basic. The you can go back to Heilbron's book to appreciate it fully. Believe me, it's worth the effort!
PS. One of my students has written a mathematical supplement to this book. It's available on my home page. (Amazon won't let me give you the URL in the review, but just do a quick searh on the web or look at the "äbout me section".) So far it only covers the first few chapters, but we hope to be able to expand on it later. I hope some of you may find it useful.

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Summary: Astronomy and the Church
Review: J.L. Heilbron's The Sun in the Church: Cathedrals as Solar Observatories is a beautifully illustrated, finely written exposition of how the Roman Church used sacred space to perform astronomy. The most sacred day in the Church calendar is Easter, established as the Sunday after the first full moon after the vernal equinox. As it turns out, this was an astoundingly difficult day to calculate, especially years in advance. As a result, in the Middle Ages the celebration of Easter "drifted" from the true date; the Church found itself commemorating Christ's resurrection on the "wrong" Sunday, a matter of grave concern. To solve this problem, astronomers determined that large buildings - most ideally churches themselves - could be made into solar observatories with a light opening at the apex and a meridian line placed on the floor. By this device, Church-supported scientists could observe the sun's precise position and movement with reference to the meridian line, and thereby make needed Easter (and other) calculations.

I confess that I am mathematically challenged, and much of this book is devoted to fairly detailed geometric and trigonometric proofs. I had no choice but to "bleep" over these sections. Heilbron's prose and argument are clear, entertaining, and persuasive, and I felt I lost none of his key points by needing to skip the proofs. Everything about Church history and astronomy in the Church - except a chapter about the unfortunate treatment of Galileo - was entirely new to me, and I was absolutely enthralled. For those who have read Dava Sobel's Galileo's Daughter, this is a useful second perspective on the Church and astronomy.

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Summary: The Dawning of the Age of Aquarius.....
Review: One does not need a mathematical background to follow the narrative of J.L.Heilbron's THE SUN IN THE CATHEDRAL but a knowledge of high school geometry will probaly help. Dr. Heilbron was aware of the "geometrically challenged" reader when he developed his book and has written the text for the lay person. Heilbron received the Watson Davis Prize for Public Understanding of Science for his work DILEMMAS OF AN UPRIGHT MAN. The average reader without a fear of math should be able to follow the ABCs in the text and link them to the ABCs in the diagrams. It took me several weeks to read the text, not because it is so difficult, but because it is filled with information and I had to take breaks to absorb what I had read.

THE SUN IN THE CATHEDRAL is nothing less than the story of how the Christian Church parented modern science and technology. Although the ignorant will persist in accusing the Church of being a roadblock, the truth is that the impetus and sustenance of scientific exploration in the West came from the church, and although one might call it an unholy alliance, Christian ideology and Science have moved in lockstep ever since. Heilbron predicts that eventually Gallileo, who was sponsored by the Church, will be cannonized a saint.

Why does this happen? Dr. Rock who invented the modern birth control pill was Roman Catholic. He developed the pill to help RC women control their fertility in a manner acceptable to the Church that had to do with the timing of the release of the ova. His method was not accepted by the Church, but nevertheless the use of Rock's pill has led to falling birth rates in the U.S. and other Catholic countries (U.S. is 40 percent RC) and a subsequent decline in the poverty rates. (Economic development is important, but per capita household income is affected by fertility levels.) Maybe he will become a saint someday.

How did the Church become interested in the study of time? The means of communication were slow in the early days of the Church and this slowness led to a requirement for advance knowledge of the moveable feast dates which the Church passed on to its far-flung parishes. The problem of determining when these dates would occur lay with determining when Easter would occur. The moveable feasts of the Church year fall in accordance with Easter (i.e. Chistmas is a fixed date, Pentacost is a moveable feast that follows Easter by 40 days, Good Friday and Lent preceed Easter by a fixed numer of days. Easter is calculated relative to the Spring Equinox which is the point at which the day and the night (solar) are exactly equal.)

To address the problem of measuring the Spring Equinox, the church employed bright young men (like Gallileo) and gave them the resources they needed including church facilities. THE SUN IN THE CHURCH is their story and the story of those who followed them who were sponsored by the Reformed Church and Royalty of both RC and Reformed persuasion.

The book suggests that even as one problem was solved, yet another arose (you need the geometric diagrams to understand the intricacies of these problems as well as their solutions). First there was the problem of finding a structure large enough to create a BIG sundial, since sundials were useful for figuring out the length of the day. This led to the use of cathedrals and other very large public buildings where even today a numer of gnomen (little windows that admit sunlight) and meridians (sun dial like stuctures inside the building) can still be found. Inside these cathedrals, pillars and other obstacles had to be overcome and how this was done is ingenious.

Obstacles to the precision of measurment led to discussions about the height of the terrain where a building was situated, the thickness of the earth under the building (some sank), the shape of the earth (affected the location of the center or apex of the triangle of measurement), the distance of the moon from the earth and the sun, etc., etc.

Most importantly, a discussion ensued about whether or not the world was heliocentric. If you start from a false premise such as the sun revolves around the earth, no matter how carefully you conduct your calculations the results will be wrong. The issue of heliocentricity proved a big stumbling block. In the end, the records of the scientists who said the earth moved about the sun were preserved (else Heilbron couldn't have written his book) but for a long time the Church held that the sun revolved around the earth, and anyone who said differently was speaking heretically. Some really funny compromises occurred, probably because intelligent church men knew they were not necessarily correct (some of the scientists were Jesuits or former clergy). And, at one point England and Italy were on two different calendars because the English refused to accept anything Rome devised, even if it was CORRECT!!.

The study of time led naturally to the study of space and both led to global explorations. The Jesuits (grey friars) traveled the globe and impressed their new converts with the science (magic) of the West. The Domincans came to the New World with the Conquistadors and recorded the science and magic of the inhabitants.

Protestants continued the tradition of exploration which led to the discovery of longitude. Seems the earth is not the same diameter every where. A team measuring the diameter of the earth in Peru was attacked by local Indians who thought the Europeans with sticks were lunatics or socerers. Ditto the Appenines in Italy. "Who would think Italian countymen could behave like savages" remarked one scientist. Geodetic surveys and even the GPS system in use today are descended from this research.

THE SUN IN THE CATHEDRAL is a fabulous book, and one every one who wants to gain a better understanding of the world around us should read. This book cancels the mistaken notion that the church tried to block science. This book is about how science and ideology interacted and framed the world we live in with "Western" ideas. And, as Heilbron points out, even in our so-called advanced state of knowledge censorship is alive and well. "All of which will be unpleasantly familiar to observers of the operation of political correctness in contemporary universities." Reason and science are threatened today by a much more insidious enemy.