[The] improbable tale [of an astrological instrument saving a church] is just one of the gems recovered by Heilbron in a book that lingers lovingly over these forgotten instruments. Once big science, now architectural curios not infrequently buried under flagstones and pews, gnomons (or meridian lines, as they are more properly called) lie at the luminous conjunction of mathematics, philosophy, architecture, astronomy and church politics. Dusted off in this idiosyncratic history of astronomy during the scientific revolution, they provide an occasion to revisit perennial questions about the relationship between science and religion, reason and faith...[Readers] will be surprised to discover what Heilbron shows: that the Catholic Church served as perhaps the largest patron of sophisticated astronomical research throughout the controversies over Copernicus and his sun-centered scheme.

Dr. Heilbron reveals the ubiquity of the solar observatories, which heretofore were little known among scholars. And he shows that the church was not necessarily seeking knowledge for knowledge's sake, a traditional aim of pure science. Rather, like many patrons, it wanted something practical in return for its investments: mainly the improvement of the calendar so church officials could more accurately establish the date of Easter.

A book both elegant and learned, exploring the installation of vast (but often easily overlooked) astronomical instruments in major churches by authorities sometimes thought, wrongly, to have opposed astronomical research.

In this elegant work, Heilbron recounts how in the seventeenth and eighteenth centuries the Roman Catholic Church fashioned several of its major cathedrals into precision instruments for studying the motions of the sun. The aim was to determine the time between vernal equinoxes, so that the dates for Easter could be forecast accurately...Heilbron, upending common views of the Church's relationship to science after it condemned Galileo, shows that Rome handsomely supported astronomical studies, accepting the Copernican hypothesis as a fiction convenient for calculation.

Heilbron's book tells of the struggle to determine dates more accurately, including a little-known aspect of the history of the calendar--the use of churches as giant sundials to make astronomical measurements.

The historical perception of post-Renaissance Italian astronomy has become so over-charged with the Roman Catholic Church's condemnation of Galileo in 1633 that it is commonly assumed that no significant science took place south of the Alps until the 19th century. But, as John Heilbron's learned, elegant and finely phrased book reminds us, this was not the case...Though Heilbron supplies all the necessary geometry to demonstrate how the meridianae [(a solar measuring instrument)] were constructed and used within the great architectural masterpieces into which they were incorporated, his book is arranged and illustrated in such a way that non-mathematical persons can enjoy it.

John Heilbron's book does tell a gripping story and with a splendid literary flair...By subtly inserting critical comments, the author evaluates the interactions of science in its gestation with the culture of those centuries and the repercussions that these interactions have has down to our own times. And so it becomes a story about people, and Heilbron tells it in a masterfully human way.

In The Sun in the Church, historian John Heilbron argues convincingly that long-held interpretations [in astronomy] are too simplistic and must be revised...Heilbron tells an important story, one that is not so much neglected as unknown among historians of science. Even in histories of astronomy, there is usually only a passing reference to it.

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...This excellent book explains the difficulties 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...The book is well written.

Heilbron chronicles the ironic relationship between astronomy and the Catholic Church as it seeks the means to determine [the date for Easter]. This is the story of politically astute astronomers and cardinals who have to reconcile church doctrine with Galileo's universe...The text is filled with fine detail and is richly illustrated. An erudite and scholarly work.

J. L. Heilbron depicts the unusual intersection of architecture, science, ecclesiastical and civil history, mathematics and philosophy that led the church to construct the buildings only a few years after it martyred Galileo. Erudite, accessible and wryly humorous, Heilbron's engaging book is a first-rate work of science history.

A fascinating history of astronomy that shows, as no other work has done so well, what happened to Italian science after Galileo's trial. An astonishing display of erudition and linguistic control, with a wealth of fine details, this is a major history that carves out a unique territory.

The innumerate reader will learn much from Heilbron's book, and may come away with a different appreciation of the stars above us.

He tells his story in rich detail, reconstructing characters and circumstances with ironic verve. His theme is the meridian lines (meridianae) laid down in the marble floors of cathedrals for quantifying the sun’s annual motion… Heilbron’s book is a treasure trove of fascinating information.

This excellent book adds a welcome complexity to the historiography of astronomy in the years after Galileo's abjuration allegedly brought Italian astronomy to its knees…Heilbron's book also reinterprets the relations of science and religion in the shadow of the Galileo affair. The novelty of his argument is neither that religion can stimulate astronomy…nor that ecclesiastical patronage encouraged learning…It is rather that the Church signally fertilized astronomy in an era when most historians portray the two as antagonists…[one] will appreciate the witty prose of the argument and the elegant design of this important book.

The Sun in the Church: Cathedrals as Solar Observatories is a historical, well-documented, scholarly book concerned both with the use of churches in Italy during the 16th and 18th centuries to obtain observations of the sun for calendric and scientific purposes and with the relationship between the Church of Rome and the heliocentric views of many of the scientists of those times.

Heilbron combines the history of astronomy, mathematics, architecture, patronage, and religion to tell a story that very much alters the common picture of the progress in astronomy in the early modern period and the place of the Catholic Church in that history. The story is well told, and the mathematics is given in a way that could discourage only the most innumerate.

J. L. Heilbron's remarkable book draws our attention to church users of a very different kind: early modern astronomers measuring the solar path to correct the shift of the ancient Julian calendar…The Sun in the Church tells their history in detail, alongside an exceptionally comprehensive and clear account of medieval and early modern astronomy…The Sun in the Church is an illuminous book, possibly as durable as the meridianae it celebrates.

This book offers a different kind of travel guide for the 'mathematical tourist,' providing an itinerary of Italian cities and churches in which to find meridians, analemmas, armillary spheres and gnomons. These are good reminders of the role of the church in the history of science and testify to the fact that everything applied to the church, even the most apparently ornamental, served a didactic purpose.