De Revolutionibus
"De Revolutionibus" (On the Revolutions of the Heavenly Spheres) is a seminal work by Nicolaus Copernicus published in 1543, which fundamentally transformed the understanding of the solar system by proposing a heliocentric model. This model asserts that the Sun is stationary at the center of the solar system, with the Earth and other planets orbiting around it, challenging the long-held Ptolemaic view that placed Earth at the center. The idea emerged from centuries of astronomical observations and was notably influenced by earlier Greek thinkers such as Aristarchus of Samos.
Despite Copernicus's careful observations and the logical foundation of his claims, the work faced significant opposition, particularly from religious authorities who saw it as contradictory to established doctrines. Although some Church leaders initially refrained from immediate condemnation, the work was later placed on the Index of Prohibited Books in 1616, reflecting the tensions between emerging scientific thought and religious beliefs.
"De Revolutionibus" is widely recognized as the catalyst for the Copernican Revolution, which laid the groundwork for future astronomers like Johannes Kepler and Galileo Galilei. These thinkers expanded upon and refined Copernicus's ideas, ultimately leading to a deeper understanding of planetary motion and the nature of the universe. The work remains a cornerstone of modern astronomy and is celebrated for its role in shifting humanity's perspective on its place in the cosmos.
De Revolutionibus
Locale Nuremberg, Germany
Date 1543
Copernicus’s work On the Revolutions of the Heavenly Spheres replaced the ancient Greek idea of an Earth-centered solar system, the geocentric model, with the modern heliocentric model that placed the Sun at the center of the solar system.
Key Figures
Nicolaus Copernicus (1473-1543), astronomerRheticus (1514-1574), Austrian astronomer and mathematician who encouraged Copernicus to write his major workMartin Luther (1483-1546), first major religious leader to attack Copernicus’ work
Summary of Event
Since at least ancient times, humans have been fascinated with the motion of the objects in the sky. They recognized that most of these objects, the stars in particular, appeared to rotate in circles around the fixed pole star, Polaris, in the Northern Hemisphere, as if the stars were fixed to a rigid sphere that surrounds the earth and that rotates once each day.
More than two thousand years ago, humans recognized there were several unusual objects in the sky, called the wanderers, because they appeared to move relative to the stars. In addition to the Sun and the Moon, these wanderers included five planets visible without telescopes: Mercury, Venus, Mars, Jupiter, and Saturn. The paths of these wanderers were observed and recorded. Astronomers wanted to know what caused the motion of the wanderers and how this motion could be predicted, while astrologers believed the positions of these wanderers influenced the daily lives of individuals on Earth.
Ancient Greek philosophers tried to develop models for the motion of the wanderers that would be in accord with all past measurements and allow prediction of their future positions. The most successful among them, the Greek philosopher Ptolemy (c. 100-178), constructed a model in which all the objects in the sky moved around the earth on progressively larger concentric circles. This model, however, did not accurately predict the motions of the wanderers, so Ptolemy fixed the planets to other circles that rolled around larger concentric circles.
The Ptolemaic model, as it came to be called, was later adopted by Roman Catholic religious leaders because it was consistent with their idea that humans were a “special creation” of God, and thus it seemed appropriate for humankind to occupy a “special position” at the center of all creation. The Ptolemaic model dominated religious thinking in Europe as Europe emerged from the Middle Ages.
This idea that the earth occupied a special position in the solar system was challenged by Nicolaus Copernicus, an astronomer and a Roman Catholic canon of the Church. Copernicus, who was born in the Prussian city of Thorn (modern Toruń, Poland), received his advanced education in Italy, where he studied astronomy, mathematics, and medicine and received a doctor’s degree in canon law. Copernicus’s long service in the religious office as canon of Ermland made him an odd candidate to defy Church teachings, but his study of astronomy led him on a path of conflict with the Church.
Copernicus was an avid observer who compiled twenty years of observations of the positions of the wanderers in the sky. By combining his observations with those recorded by earlier observers, Copernicus was able to observe flaws in the predictions of Ptolemy’s model. By 1513, when Copernicus returned to Poland from Italy, he had formulated his own model of the motion in the solar system, reviving an idea proposed more than seventeen hundred years earlier by Greek astronomer Aristarchus of Samos. In the Copernican model, the Sun was stationary at the center of the solar system, with the earth and the other planets moving around the Sun in concentric circular orbits. Copernicus wrote: “As if seated on a royal throne, the sun rules the family of planets as they circle around him.” The earth, in this model, was reduced to the status of one of the several planets circling around the Sun. It held no special status from a location at the center of all creation.
Copernicus circulated his idea among his friends in a manuscript entitled Commentariolus (1514; English translation, 1939). This manuscript asserted that “The center of the Earth is not the center of the universe. . . . All the spheres revolve around the Sun, as if it were in the middle of everything.” Copernicus recognized, however, that his idea was contrary to the teaching of the Church, so he refrained from widespread distribution of this manuscript. Nevertheless, Pope Clement VII became aware of Commentariolus in 1533 but took no action to suppress Copernicus’s idea.
The first serious attack on Copernicus’s model came from Protestant religious leaders. Martin Luther said of Copernicus, “This fool wants to turn the whole art of astronomy upside down! But as the Holy Scripture testifies Joshua bade the sun to stand still, not the earth.” Luther’s appeal to Scripture, and thus faith in the word of God, to explain the behavior of nature, was in sharp contrast to Copernicus’s belief that the behavior of natural objects could be understood by a combination of observation or experimentation and of reasoning in what has come to be called the scientific method.
Perhaps because of the attacks by religious leaders, Copernicus did not publish the full description of his idea, in De revolutionibus orbium coelestium (1543; On the Revolutions of the Heavenly Spheres, 1952; better known as De revolutionibus), until 1543. Georg Joachim, called Rheticus, a professor of mathematics, had heard of Copernicus’s idea and then journeyed to Ermland in 1539 to learn more about it from Copernicus himself. Rheticus encouraged Copernicus, who was nearing seventy years of age, to commit his ideas to writing. Copernicus agreed, and he divided the text of De revolutionibus into six parts: the first, and most controversial, concerned the arrangement of objects within the solar system; the second contained his new star catalog; the third covered precession, that is, how the motion of the earth’s pole causes the fixed star about which the sky appears to rotate to change with time; the fourth discussed the moon’s motions; and the fifth and sixth examined the motions of the planets.
The book was typeset in Nuremberg, Germany, initially under the supervision of Rheticus. Andreas Osiander, who took over supervision when Rheticus left Nuremberg, wrote to Copernicus in 1541, urging him to avoid a direct attack on the teachings of the Church about the arrangement of the solar system. Osiander suggested the introduction to De revolutionibus should indicate that either the hypothesis of Copernicus or that of Ptolemy could explain the observed planetary motion. Copernicus rejected this, but Osiander removed the introduction Copernicus had written and substituted his own preface, which emphasized that De revolutionibus presented a hypothesis. Since Osiander did not sign the new preface, readers generally assumed it was written by Copernicus, who did not see a copy of the printed work until he was near death in 1543.
Osiander’s preface might have kept Roman Catholic theologians from attacking the book for some time. De revolutionibus was not placed on the Index librorum prohibitorum (the Index of Prohibited Books) of the Roman Catholic Church until 1616, when the Holy Office in the Vatican began its investigation of the astronomer Galileo Galilei, who had spoken openly of his admiration for the work of Copernicus. At that time the Holy Office pronounced the idea of a Sun-centered solar system to be “foolish and philosophically absurd.” In the intervening years, Roman Catholic leaders faced another challenge to the special status of the earth and of humankind. Giordano Bruno, an Italian astronomer, philosopher, and Catholic cleric, was burned alive in 1600 for suggesting that the universe might contain other inhabited worlds.
Significance
Although Christian religious leaders rejected Copernicus’s work, it was widely adopted by astronomers and astrologers throughout Europe as the method to predict planetary positions because of the simplicity of calculating the positions using this method.
The publication of De revolutionibus began what is called the Copernican Revolution. Copernicus’s work influenced later European astronomers, including Johannes Kepler and Galileo Galilei, and set the stage for the adoption of the Sun-centered model of the solar system by the scientific world. Kepler replaced the concentric circles of the Copernican model with elliptical paths for the planets and removed all the remaining discrepancies between observed planetary positions and the predictions of the Sun-centered model. Galileo, whose Dialogo . . . sopra i due massimi sistemi del mondo (Dialogue Concerning the Two Chief World Systems, 1953) was published in 1632, firmly established the Sun-centered solar system in the minds of European astronomers.
Bibliography
Armitage, Angus. Copernicus. New York: T. Yoseloff, 1957. A biographical account of Copernicus describing the impact of his ideas on modern science.
Barrett, Peter. Science and Theology Since Copernicus: The Search for Understanding. Reprint. Poole, Dorset, England: T&T Clark, 2003. Traces the legacy of Copernicus over four hundred years. Traces the history of the debate between science and Christianity, attempting to fashion a philosophical basis for the simultaneous embrace of scientific method and religious faith in the modern world.
Blumenberg, Hans. The Genesis of the Copernican World. Translated by Robert M. Wallace. Cambridge, Mass.: MIT Press, 1987. A study of the ideas of the Copernican Revolution with a focus on its impact on European history.
Durham, Frank, and Robert D. Purrington. Frame of the Universe. New York: Cambridge University Press, 1983. Traces the evolution of ideas about the arrangement of the solar system, with a two-chapter discussion of the Copernican Revolution.
Gingerich, Owen. The Book Nobody Read: Chasing the Revolutions of Nicolaus Copernicus. New York: Walker, 2004. A fascinating and original work of scholarship. Gingerich spent years tracking down and examining every extant copy of the original printing of De revolutionibus. Using this bibliographic analysis, he demonstrates who read the work, what they thought of it, and how Copernicus’s ideas spread throughout Europe. Includes illustrations, photographic plates, maps, bibliographic references, and index.
Henry, John. Moving Heaven and Earth: Copernicus and the Solar System. Cambridge, England: Icon, 2001. Argues that Copernicus’s discovery had revolutionary effects for the cultural status afforded to theoretical science and mathematics in Western culture. Asserts that before Copernicus, pure knowledge was believed to come only from the traditions of ancient scholars, whose work was preserved only in fragments. Copernicus demonstrated that abstract mathematics and formal scientific inquiry could produce pure knowledge on their own, thereby transforming the nature of thought and truth in the West.
Kuhn, Thomas S. The Copernican Revolution. Cambridge, Mass.: Harvard University Press, 1966. An in-depth account of the ideas of Galileo and their influence on European astronomy.
Ley, Willy. Watchers of the Skies. New York: Viking Press, 1966. An excellent account of early astronomy, with a chapter on Copernicus and his major work.