Astronomy 161:

An Introduction to Solar System Astronomy

Prof. Richard Pogge

A Brief Note on Religious Objections to Copernicus:

The specific response one of the most important contemporaries of Copernicus, Martin Luther, is telling. The quote below is actually in response to the publication of the brief Commentariolus , which appeared a decade before De Revolutionibus . It comes from Luther's Tablebook ( Tischreden ), or record of dinner-table conversations:

"There is talk of a new astrologer who wants to prove that the earth moves and goes around instead of the sky, the sun, the moon, just as if somebody were moving in a carriage or ship might hold that he was sitting still and at rest while the earth and the trees walked and moved. But that is how things are nowadays: when a man wishes to be clever he must needs invent something special, and the way he does it must needs be the best! The fool wants to turn the whole art of astronomy upside-down. However, as Holy Scripture tells us, so did Joshua bid the sun to stand still and not the earth."

The scriptural passage to which Luther refers is Joshua 10:10-15. Elsewhere Luther refers to Copernicus as "a fool who went against Holy Writ". It is this latter quote that usually makes it into the textbooks.

Despite these more dramatic objections, overall the initial response to Copernicus was somewhat ambivalent. The full implications of his revolutionary ideas only began to sink in over the decades following the publication and slow dissemination of De Revolutionibus . Luther's sarcastic comments aside, Copernicus' ideas were seriously discussed in Lutheran as well as Catholic universities during subsequent years, both for and against (though mostly against at first). While in detail Copernicus' system used more circles than Ptolemy's, it did not use the equant, which was mathematically more challenging to use in practice. As a consequence, mathematically speaking the Copernican system was relatively easier to use. Indeed, computations based on the Copernican system were used to create accurate tables of planetary positions (the Prutenic Tables computed by Erasmus Reinhold), and Copernical computations were used in part of the Gregorian Calendar Reform of the 1570s. At issue at the time was whether one viewed Copernicus' Sun-centered system as merely a convenient computational artifice, or whether the Sun and not the Earth really was at the center. Copernicus clearly believed in the latter, but this conviction was muted by Osiander's preface to De Revolutionibus that suggested otherwise.

In many ways the initial cautious ambivalence of Catholic authorities is unsurprising. Copernicus was a loyal Catholic and a canon of Frauenberg Cathedral, making him a relatively minor member of the Catholic hierarchy. He had followed all of the proper procedures required to secure formal permission from Church authorities to publish his book, and he even dedicated it to the reigning Pope at the time (Paul III). That their response was ambivalent is not to say that the Church did not take the matter seriously, or fail to study it. By all accounts the Church did both. However, in the 16th century the Catholic Church found itself beset by many radical ideas, a number of which were direct and unambiguous frontal assaults upon its spiritual and political authority in Europe. So long as Copernicus' ideas remained a mathematical argument (in Latin) among scholars and did nothing to threaten either the beliefs of the common man or the Church's ultimate authority in such matters, the Church had no need to respond.

By the beginning of the 17th century, however, the Church found it could no longer treat these ideas with silence. We'll see part of that story when we talk about Galileo in a subsequent lecture.