Heliocentric Theory in the Age of Reformation

Galileo Pleiades

 by Konrad Von Taiser

    Astronomy is by a wide margin the oldest branch of all the sciences, and naturally so; the moon and stars which adorn the night sky have inspired and mystified humankind since we first began to walk the earth, serving as loyal companions on our turbulent journey to the modern age . The consistency of heavenly bodies provided ancient man with a temporal point of reference, pulling him from the chaos of unmeasured time and facilitating the creation of the first calendar systems. Observation of the moon and stars led to the apportionment of days and weeks into months and years which could be recorded and remembered; expanding the monopoly of present into a calculable past and giving birth to the very concept of history. Throughout the millennia, scribes of every culture blessed with the written word have found a muse in the beauty of the night sky. Celestial language is a prominent feature of early creation myths and the sun, moon, and stars appear frequently in the sacred texts of most major religions, including Judaism and Christianity. Indeed, before the God of Genesis fashioned man from clay or brought the formless earth to life, he divided light from darkness and gave rise to the heavens. In short, the study of celestial bodies has always been an integral part of the human experience, which is why men such as Nicolaus Copernicus, Galileo Galilei, Tycho Brahe, and Johannes Kepler, who used the scientific method to unlock the mysteries of the heavens in the 16th and 17th centuries, should be counted among the most important and cherished figures in all of history. For the questions they answered were as old as civilization itself and the discoveries they made forever transformed the perspective of mankind. Unfortunately, these remarkable individuals, whose work laid the foundations of modern Astronomy, were born into a time of immense social and cultural upheaval in Europe. The spirit of the renaissance, which inspired the scientific revolution, also resulted in the Protestant Reformation and the Counter-Reformation. Many 16th and 17th century scientists became entangled in the ideological turbulence and doctrinal battles generated by the Reformation, becoming unwitting casualties in the Catholic Church’s war on dissent. This paper will survey the birth of modern astronomy in the context of the reformation; examining the contributions of Galileo Galilei in the field of cosmology, the controversy surrounding his work, the impact of his discoveries on church doctrine, clerical reaction to his assertions, and the origins of the conflict between science and religion.

    Who has not gazed in awe upon the majesty of night sky and felt an innate sense of smallness in the face of such a vast unknown? Contemplation of the cosmos, specifically, the insignificance of earth in comparison to the infinite expanse of the universe, often leads to feelings of uncertainty. The same was true for Europeans during the reformation-era, however, perceptions of the cosmos in that period differed markedly from the present. In the 16th and 17th centuries, the cosmos resided outside the realm of human understanding; a place entirely foreign, inhabited and controlled by elements of the supernatural. People did not view the world around them, the earth itself, as one of many planets, nor did they think of the sun as a star, one of trillions comprising a vast web of galaxies. The scientific revolution finally allowed the heavens to be understood in scientific terms and removed the aura of the divine from cosmology.

"Moon" by Johannes Hevelius (1645)

“Moon” by Johannes Hevelius (1645)

     Throughout most of human history philosophers and men of science viewed the Earth as the focal point of the universe; the object around which all other celestial objects revolved. But by the dawn of the 18th century, the majority of Western thinkers had discarded Ptolemy’s incorrect geocentric system in favor of Copernicus’s heliocentric system. At first glance, the substitution of one cosmological theory for another may not seem like an overly significant matter. After all, earth’s exact position in relation to the sun and stars has little effect on the everyday lives of its inhabitants. In truth, however, the adoption of Copernican theory represents an important and monumental shift in the human perspective, a revolution in thought which ultimately impacted every area of philosophy, religion, and science. In the 17th century heliocentric mode of thought, Earth no longer sat at the heart of creation and the sun it revolved around was not a unique anomaly, but a mere star, one of billions in an infinitely large universe full of stars. As a result of this revelation, a certain specialness surrounding the human race vanished and arrogance gave way to uncertainty. In 1575, Jerome Wolfe voiced the anxiety generated by such notions in a letter to Tycho Brahe, writing:

“No attack on Christianity is more dangerous than the infinite size of the Heavens.”

    Several years before Martin Luther’s 95 Theses kicked off the Protestant Reformation, Polish astronomer Nicolaus Copernicus began composing a revolutionary work of his own. However, he lacked the audacity of Luther and did not publish his provocative and influential writings until he was on the verge of death in the early 1540s, safe from the authoritative wrath he rightly presumed his work would generate in Rome. Copernicus was certainly not the first person to propose that the earth moved around the sun, the idea had been floating around scientific circles in Europe since antiquity. Archimedes of Syracuse records in The Sand Reckoner that an ancient Greek astronomer, Aristarchus of Samos, developed heliocentric theory almost three hundred years prior to the birth of Jesus of Nazareth:

“His hypotheses are that the fixed stars and the sun remain unmoved, that the earth revolves about the sun in the circumference of a circle, the sun lying in the middle of the orbit, and that the sphere of the fixed stars, situated about the same centre as the sun, is so great that the circle in which he supposes the earth to revolve bears such a proportion to the distance of the fixed stars as the centre of the sphere bears to its surface.”

    Nevertheless, the geocentric model promoted by Claudius Ptolemy of Alexandria overshadowed that posited by Aristarchus and, as a result, the notion that the sun revolved around a fixed earth persisted largely unchallenged until the age of the Reformation. Copernicus first outlined his heliocentric beliefs in a 1514 manuscript entitled Commentariolus, meaning “Little Commentary.” In this landmark 40 page synopsis, he firmly declared that there was “no one center of all the celestial circles or spheres” and that the “earth is not the center of the universe.” Copernicus distributed copies of his treatise to close friends, but withheld it from publication. Commentariolus ultimately became lost to history until a battered copy was uncovered in Vienna and published in 1878. According to historian Will Durant, Pope Leo X himself expressed a harmless curiosity upon hearing reports of Copernicus’s heliocentric hypothesis, but to the dismay of those it inspired, the attitude of the Church changed dramatically by the dawn of the 17th century and Catholic officials were far less open-minded in bloody wake of the Inquisition.

Nicolaus Copernicus

Nicolaus Copernicus

    The Copernican Revolution impacted the realm of science to the extent that Luther’s Protestant Reformation impacted the realm of religion. Unfortunately, in the sixteenth century, the two realms were often one in the same, and Protestants and Catholics alike condemned the heliocentric model of the universe with equal fierceness. Copernicus’s theory was enormously controversial in the heated religious atmosphere of the reformation, in which any form of dissent carried the risk of torture and execution. Ironically, like his intellectual successor Galileo, Copernicus was a man of deep faith who was not purposefully seeking confrontation with clerical authorities. All the same, his work was commonly met with hostility because it rejected conventional cosmological thought and dismissed the wisdom of trusted classical philosophers like Aristotle and Ptolemy, but more importantly, it clashed with official Church doctrine and appeared to contradict Biblical scripture. Sadly, his nominal work outlining the heliocentric interpretation of the solar system, On the Revolution of Heavenly Spheres, was generally disregarded by academics and censured by the clergy following its publication in 1543, the very year of Copernicus’s death.

    In fairness, the Copernican notion, that the earth moved while the sun sat still, stood in direct opposition to the evidence of the senses. Moreover, its originator failed to produce credible and undeniable evidence to support such a seemingly outlandish thesis. Indeed, most learned astronomers remained unconvinced of Copernicus’s assertions until Galileo Galilei and Johannes Kepler provided reliable observational data and a solid mathematical foundation for his heliocentric hypothesis. Through the remarkable work of these men, and the invaluable contributions of numerous like-minded colleagues, Copernican theory was transformed into scientific fact. Sigmund Freud later noted the immense psychological impact of adopting a sun-centered system:

“Humanity has in the course of time had to endure from the hands of science…outrages upon naïve self-love…the first was when it realized that our earth was not the centre of the universe, but a tiny speck in a world-system of a magnitude hardly conceivable.”

    Galileo did not begin to publicly promote Copernicus’s theory in his own work in until 1609, though he previously expressed admiration for the ideas of his predecessor and recognized the merits of a sun-centered model of the solar system. His initial hesitance to openly tout his heliocentric-leanings can be justly attributed to the before mentioned fact that both conventional scientific thought and official Chruch doctrine ran contrary Copernican theory. However, following his perfection of the astronomical telescope that year, Galileo’s understanding of the universe, and earth’s place within it, underwent a major overhaul.

Galileos-telescope-002        Galileo is often credited as the inventor of the telescope, but in truth, the spyglass had been in use for years prior to 1609, when he built his own from scratch and added some slight modifications to its design in order to facilitate his cosmological curiosity. Using his newly-improved telescope, he was able to observe the face of the moon in unprecedented detail and with astonishing clarity; realizing instantly that, contrary to popular opinion, it was not a smooth, unblemished, and perfectly rounded sphere. In fact, it was just the opposite; a rough and diverse landscape, containing various earth-like features such as mountain ranges, deep valleys, and countless impact craters. He then used his device to observe Jupiter, sighting four nearby “stars,” which had gone undetected until the very moment he laid eyes on them. To his surprise, Galileo found that these objects were not stars, but moons which encircled their host in regular, discernable orbital patterns. The bewildered astronomer quickly understood the implications of his findings, which in essence, confirmed the theories of Copernicus. This shocking revelation, which shattered the Aristotelian-Ptolemaic view of earth as the center of the cosmos, was followed by eight weeks of sleepless nights, during which, Galileo feverishly sketched diagrams of the rocky lunar surface, carefully tracked the moons orbiting Jupiter, and enthusiastically recorded his observations in precise detail. Fearful that a fellow astronomer might also turn a spyglass towards the night sky and claim credit for his remarkable discoveries, Galileo immediately compiled his findings into a hastily composed treatise entitled Sidereus Nuncius, or “The Starry Messenger.” First published in 1610, this landmark work opens with the following statement:

“Surely it is a great thing to increase the numerous host of fixed stars previously visible to the unaided vision, adding countless more which have never before been seen, exposing these plainly to the eye in numbers ten times exceeding the old and familiar stars. It is a very beautiful thing, and most gratifying to the sight, to behold the body of the moon, distant from us almost sixty earthly radii, as if it were no farther away than two such measures—so that its diameter appears almost thirty times larger, its surface nearly nine hundred times, and its volume twenty-seven thousand times as large as when viewed with the naked eye. In this way one may learn with all the certainty of sense evidence that the moon is not robed in a smooth and polished surface but is in fact rough and uneven, covered everywhere, just like the earth’s surface, with huge prominences, deep valleys, and chasms.”

The Starry Messenger

The Starry Messenger

    In his introduction to The Starry Messenger, Galileo grandly announced his newly minted telescope to the world by enthusiastically declaring that it had allowed him to observe phenomena which “surpasse[ed] all wonders by far.” It truly was a revolutionary invention, and its arrival marks one of those rare moments in human history which impacts every moment to follow. Aware that his unorthodox claims would appear to contradict scripture and challenge the conventional cosmological views promoted by the Catholic Church, Galileo cleverly cited divine revelation as his inspiration for the telescope. Prior to presenting The Starry Messenger’s main body of work, he stated:

“These facts were discovered and observed by me not many days ago with the aid of a spyglass which I devised, after first being illuminated by divine grace.”

    The Starry Messenger sold out almost immediately and Galileo’s fame spread rapidly as a result of its popularity. By 1613, prominent members of the Italian intelligentsia were enthusiastically discussing his “wonderful invention” of the telescope and touting his “proof of the motions” of Jupiter’s moons. Still, for every one of Galileo’s admirers, there was an equally scornful detractor. These conservative-minded critics resented his work’s implications, which they denounced as heretical and blasphemous. In December, Galileo’s most fervent follower, Benedetto Castelli, sent a letter to his mentor warning that Cosimo Boscaglia, a philosopher at the University of Pisa, was publicly accusing Galileo of heresy in the company of nobles. According to Castelli, Boscaglia stated that the movement of the earth around the sun “could not happen, especially since the Holy Scripture was clearly contrary to this claim.” Galileo was gentle, yet firm in his initial responses to those who believed his work contradicted scriptural fact, countering:

“Scripture can never lie or err… its declarations are absolutely and inviolably true…though the Scripture cannot err, nevertheless some of its interpreters and expositors can sometimes err in various ways. . One of these would be very serious and very frequent, namely to want to limit oneself always to the literal meaning of the words”

Galileo's Sketches of Lunar Landscape

Galileo’s Sketches of Lunar Landscape

     Galileo rejected his critic’s literal interpretation of scripture in matters of science and nature as foolish and simpleminded. Noting that Biblical language was routinely symbolic, he maintained that certain passages relating to the position of earth were merely metaphorical in nature, crafted to convey meaning or add emphasis, not to denote incontrovertible scientific fact, as men like Boscaglia claimed. This is made evident in Galileo’s lengthy correspondence with Castelli in the winter of 1613:

“Thus in the Scripture one finds many propositions which look different from the truth if one goes by the literal meaning of the words, but which are expressed in this manner to accommodate the incapacity of common people; likewise, for the few who deserve to be separated from the masses, it is necessary that wise interpreters produce their true meaning and indicate the particular reasons why they have been expressed by means of such words.”

   In Galileo’s view, the phraseology of certain Biblical passages which appeared to define the earth’s position as fixed was clearly intended solely as a literary measure, designed to help ancient readers comprehend ideas of great complexity in an age wrought with ignorance. Thus, he contended, when David writes in the Book of Psalms that God “set the earth on its foundations; it can never be moved,” he does so simply to express the permanence of earth, not its relationship with the sun. Galileo was frustrated by the fact that so many of his contemporaries lacked the wisdom needed to differentiate between obvious linguistic devices and statements of doctrinal truth, especially in the new age of knowledge and reason they occupied. In his 1615 essay addressed to the Grand Duchess Christina, granddaughter to Catherine de’ Medici, he lamented the fact that “the number of men ill-suited to understand adequately the Holy Scripture and the sciences is by nature much greater than the number of intelligent ones.” Galileo outlined his view of the Bible’s relationship to the natural world by stating:

“The reason for condemning the opinion that the earth moves and the sun stands still is that in many places in the Bible one my read that the sun moves and the earth stands still…With regard to this argument, I think in the first place that it is very pious to say and prudent to affirm that the holy Bible can never speak an untruth- whenever its true meaning is understood….This being granted, I think that in discussion to physical problems we ought to begin not with scriptural passages, but from sense-experiences and necessary demonstration; for the Holy Bible and the phenomena of nature proceed alike from the divine word….It is necessary for the Bible, in order to be accommodated to the understanding of every man, to speak things which appear to differ from absolute truth so far as the bare meaning of the words is concerned. But Nature, on the other hand, is inexorable and immutable….I do not feel obliged to believe that the same God who has endowed us with senses, reason, and intellect has intended us to forgo their use…”

     Galileo’s detractors, mainly conservative clergymen and philosophers, accosted him with an even greater ferocity as a result of his correspondence with Castelli and his letter to the Grand Duchess Christina. Over the next two years their allegations became increasingly dangerous. In 1615, a letter of complaint authored by Lorini, a Dominican friar outraged by Galileo’s unsanctioned interpretation of Biblical scripture, instigated a year-long investigation into his work by the Inquisition in Rome. Lorini’s letter does not attack the cosmological theories of Galileo directly, but rather, his claim that a contest between observation of nature and scriptural evidence should end in the victory of observation:

“I have come across a letter that is passing through everybody’s hands here, originating among those known as ”Galileists,” who, following the views of Copernicus, affirm that the earth moves and the heavens stand still. In the judgment of all our Fathers at this very religious convent of St. Mark, it contains many propositions which to us seem either suspect or rash: for example, that certain ways of speaking in the Holy Scripture are inappropriate; that in disputes about natural effects the same Scripture holds the last place; that its expositors are often wrong in their interpretations; that the same Scripture must not meddle with anything else but articles concerning faith; and that, in questions about natural phenomena, philosophical or astronomical argument has more force than the sacred and the divine…”

     Fortunately for Galileo,  due to a lack of evidence and the fact that he had not yet affirmed his belief in Copernican theory outright, the church chose not summon the Italian scientist to Rome or level serious charges. Unfortunately for astronomy in general, the Inquisition did issue a firm denouncement of the heliocentric model, labeling the theories of Copernicus as heretical lies and forbidding their future promotion by Galileo, or anyone else. In addition, On the Revolution of Heavenly Spheres and others works which advocated a sun-centered view of the solar system were placed on the Index Librorum Prohibitorumlist, the Church’s unsurprisingly long roster of prohibited publications.

     Though he narrowly evaded condemnation in 1616, Galileo’s own work, Dialogue on the Great World Systems, soon joined his forbearer’s on the list of writings banned by Rome. Published in 1632, the book masterfully compared the merits of the Ptolemaic model with those of the Copernican model, which in itself may not have proven provocative enough to solicit the wrath of Rome. However, the fact that fact that the argument in support of the geocentric model favored by the church was voiced through a character named Simplicius, a title clearly analogous to “simpleton,” was more than enough to generate a response. The ill-advised tactic of using Simplicius to express the Church’s official view of the cosmos in an overly dim-witted manner was not overlooked or easily forgiven by Pope Urban VIII, who quickly banned Galileo’s inflammatory book and issued a subpoena ordering him to appear to before the Holy Inquisition in Rome to answer for his perceived insolence.


    On April 12, 1633, the trial of Galileo began. The 70 year old astronomer was charged with for violating Rome’s 1616 injunction against teaching or defending “the immobility or rest of the sun,” chiefly the Copernican idea that the “planets and the earth revolve with their own motions.” Melchior Inchofer, a Hungarian Jesuit who played a prominent role in the prosecution, summarized the Inquisition’s view:

“Moreover, in discussing the passages from Scripture, especially those about the sun’s motion, he [Galileo] did his best to show that Scripture speaks with a meaning adapted to popular opinion and that in reality the sun does not move. Then he ridiculed those who are strongly committed to the common scriptural interpretation of the sun’s motion as if they were small-minded, unable to penetrate the depth of the issue, half-witted, and almost idiotic.”

    Inchofer’s statement reflects the true crime of Galileo Galilei; arrogance in the face of popular ignorance. In actuality, it was rarely Galileo’s assertion that Copernican theory was correct that rattled his detractors, but the condescending tone he used when making and defending that assertion. The zeal with which Galileo stood his ground was bound to sow discord in the religiously volatile atmosphere of 17th century Italy. His tendency to portray the clergymen and philosophers who challenged him as backward simpletons generated resentment and hostility within the already insecure Catholic Church of the early 1600s, which had spent the previous century struggling to contain the damage caused by similarly insubordinate individuals such as Martin Luther and John Calvin. Consequently, by the time Galileo published his Dialogues in 1632, his accosters in Rome were exceedingly aware of the fact that a single voice of dissent could have a devastating impact on the authority of the Church. It was this knowledge which had prompted Catholic officials to establish an efficient and ruthless mechanism for squashing troublemakers like Galileo; the Supreme Sacred Congregation of the Roman and Universal Inquisition, better known as the Roman Inquisition.


     By the time of Galileo’s trial, numerous pioneers of science and reason, most notably Giordano Bruno, had already been condemned to burn by the irrational and merciless tribunals of the Inquisition. For that reason, the aged teacher had ample reason to fear for his life; for although he had solid observational evidence to support his claims; his accusers had the Holy Scripture to counter those claims, as well as the authoritative might to rigidly enforce their interpretation of that scripture. The threat of a gruesome and painful death combined with the belittling and menacing tone of the prosecution to reduce the normally stubborn astronomer to a state of meek subservience. Towards the end of his arduous trial, Galileo lamented his “pitiable state of ill-health,” which he attributed to “ten months of constant mental distress, and the discomforts of a long and tiresome journey” to Rome. He beseeched the court for clemency, noting that he had already “lost the greater part of the years which [his] previous state of health promised” as a result of its investigation. In the end, the court spared the astronomer’s life, but issued a scathing sentence on June 22, 1633:

“Whereas you, Galileo…aged seventy years, were denounced to this Holy Office in 1615 for holding as true the false doctrine taught by some that the sun is the center of the world and motionless and the earth moves… for interpreting Holy Scripture according to your own meaning …in accordance with Copernicus’s position…a proposition which is philosophically absurd and false, and formally heretical… Therefore, invoking the Most Holy name of Our Lord Jesus Christ and his most glorious Mother, ever Virgin Mary… we pronounce final judgment on the case… We are willing to absolve you from them provided that first, with a sincere heart and unfeigned faith, in front of us you abjure, curse, and detest the abovementioned errors and heresies, and every other error and heresy contrary to the Catholic and Apostolic Church, in the manner and form we will prescribe to you…we order that the book Dialogue by Galileo Galilei be prohibited by public edict. We condemn you to formal imprisonment in this Holy Office at our pleasure…”

    That same day, in order to keep his life, Galileo denounced the work to which he had devoted it, stating in his abjuration:

“…to remove from the minds of … all faithful Christians, this strong suspicion, reasonably conceived against me, with sincere heart and unfeigned faith I abjure, curse, and detest the aforesaid errors and heresies…and I swear that in the future I will never again say or assert, verbally or in writing, anything that might furnish occasion for a similar suspicion”

    So it was that the one of the greatest thinkers in all of human history was mocked, ridiculed, judged, and condemned by the small-minded and ignorant men of the Roman Inquisition. Galileo, the learned philosopher, revolutionary astronomer, and brilliant scientist, was confined to house arrest for the remainder of his days. However, this defender of reason, who revealed the inner-workings of nature to an ungrateful world, eventually had the last laugh. Galileo’s name, work, and memory are honored and cherished by countless people the world over. Whereas his critics, if they are remembered at all, are known solely for their failure to recognize the genius of a better and wiser man.

    Galileo was among the first Europeans to perceive of the fundamental laws which govern creation as mathematical in nature. Unlike the religious radicalism underpinning the logic of his critics, Galileo’s mathematical view of the universe was formulaic, logical, and indifferent to the dogmatic discord and pretty squabbles which dominated the Reformation. He is considered the originator of the scientific method, whereby all claims, assumptions, and hypotheses concerning the natural world are considered invalid until confirmed through observation and experimentation. Thus, his contributions to the study of cosmology, enormous as they were, pale in comparison to his influence on philosophical thought and scientific reasoning in general. Galileo’s unique perspective earned him the title “Father of Modern Science.” His work and his courageous stand against the Roman Catholic Church  laid the foundation of physics and paved the way for future enlightened thinkers.

Statue of Galileo in Florence, Italy.

Statue of Galileo in Florence, Italy.


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