The Copernican Revolution was the paradigm shift from the Ptolemaic model of the heavens, which described the cosmos as having Earth stationary at the center of the universe, to the heliocentric model with the Sun at the center of the Solar System. This revolution consisted of two phases; the first being extremely mathematical in nature and the second phase starting in 1610 with the publication of a pamphlet by Galileo. [1] Beginning with the 1543 publication of Nicolaus Copernicus’s De revolutionibus orbium coelestium , contributions to the “revolution” continued until finally ending with Isaac Newton’s work over a century later.
The "Copernican Revolution" is named for Nicolaus Copernicus, whose Commentariolus , written before 1514, was the first explicit presentation of the heliocentric model in Renaissance scholarship. The idea of heliocentrism is much older; it can be traced to Aristarchus of Samos, a Hellenistic author writing in the 3rd century BC, who may in turn have been drawing on even older concepts in Pythagoreanism. Ancient heliocentrism was, however, eclipsed by the geocentric model presented by Ptolemy in the Almagest and accepted in Aristotelianism.
Martianus Capella (5th century CE) expressed the opinion that the planets Venus and Mercury did not go about the Earth but instead circled the Sun. [2] Capella's model was discussed in the Early Middle Ages by various anonymous 9th-century commentators [3] and Copernicus mentions him as an influence on his own work. [4] Macrobius (420 CE) described a heliocentric model. [5] John Scotus Eriugena(815-877 CE) proposed a model reminiscent of that from Tycho Brahe. [5]
European scholars were well aware of the problems with Ptolemaic astronomy by the 13th century. The debate was precipitated by the reception by Averroes' criticism of Ptolemy, and it was again revived by the recovery of Ptolemy's text and its translation into Latin in the mid-15th century. [lower-alpha 1] Otto E. Neugebauer in 1957 argued that the debate in 15th-century Latin scholarship must also have been informed by the criticism of Ptolemy produced after Averroes, by the Ilkhanid-era (13th to 14th centuries) Persian school of astronomy associated with the Maragheh observatory (especially the works of Al-Urdi, Al-Tusi and Ibn al-Shatir). [7]
The state of the question as received by Copernicus is summarized in the Theoricae novae planetarum by Georg von Peuerbach, compiled from lecture notes by Peuerbach's student Regiomontanus in 1454 but printed only in 1472. Peuerbach attempts to give a new, mathematically more elegant presentation of Ptolemy's system, but he does not arrive at heliocentrism. Regiomontanus himself was the teacher of Domenico Maria Novara da Ferrara, who was in turn the teacher of Copernicus.
There is a possibility that Regiomontanus already arrived at a theory of heliocentrism before his death in 1476, as he paid particular attention to the heliocentric theory of Aristarchus in a later work, and mentions the "motion of the Earth" in a letter. [8]
Copernicus studied at Bologna University during 1496–1501, where he became the assistant of Domenico Maria Novara da Ferrara. He is known to have studied the Epitome in Almagestum Ptolemei by Peuerbach and Regiomontanus (printed in Venice in 1496) and to have performed observations of lunar motions on 9 March 1497. Copernicus went on to develop an explicitly heliocentric model of planetary motion, at first written in his short work Commentariolus some time before 1514, circulated in a limited number of copies among his acquaintances. He continued to refine his system until publishing his larger work, De revolutionibus orbium coelestium (1543), which contained detailed diagrams and tables. [9]
The Copernican model makes the claim of describing the physical reality of the cosmos, something which the Ptolemaic model was no longer believed to be able to provide. Copernicus removed Earth from the center of the universe, set the heavenly bodies in rotation around the Sun, and introduced Earth's daily rotation on its axis. [9] While Copernicus's work sparked the "Copernican Revolution", it did not mark its end. In fact, Copernicus's own system had multiple shortcomings that would have to be amended by later astronomers.
Copernicus did not only come up with a theory regarding the nature of the Sun in relation to the Earth, but thoroughly worked to debunk some of the minor details within the geocentric theory. [10] In his article about heliocentrism as a model, author Owen Gingerich writes that in order to persuade people of the accuracy of his model, Copernicus created a mechanism in order to return the description of celestial motion to a “pure combination of circles.” [11] Copernicus’s theories made a lot of people uncomfortable and somewhat upset. Even with the scrutiny that he faced regarding his conjecture that the universe was not centered around the Earth, he continued to gain support- other scientists and astrologists even posited that his system allowed a better understanding of astronomy concepts than did the geocentric theory.
Tycho Brahe (1546–1601) was a Danish nobleman who was well known as an astronomer in his time. Further advancement in the understanding of the cosmos would require new, more accurate observations than those that Nicolaus Copernicus relied on and Tycho made great strides in this area. Tycho formulated a geoheliocentrism, meaning the Sun moved around the Earth while the planets orbited the Sun, known as the Tychonic system. Although Tycho appreciated the advantages of Copernicus's system, he like many others could not accept the movement of the Earth. [12]
In 1572, Tycho Brahe observed a new star in the constellation Cassiopeia. For eighteen months, it shone brightly in the sky with no visible parallax, indicating it was part of the heavenly region of stars according to Aristotle's model. However, according to that model, no change could take place in the heavens so Tycho's observation was a major discredit to Aristotle's theories. In 1577, Tycho observed a great comet in the sky. Based on his parallax observations, the comet passed through the region of the planets. According to Aristotelian theory, only uniform circular motion on solid spheres existed in this region, making it impossible for a comet to enter this region. Tycho concluded there were no such spheres, raising the question of what kept a planet in orbit. [12]
With the patronage of the King of Denmark, Tycho Brahe established Uraniborg, an observatory in Hven. [13] For 20 years, Tycho and his team of astronomers compiled astronomical observations that were vastly more accurate than those made before. These observations would prove vital in future astronomical breakthroughs.
Kepler found employment as an assistant to Tycho Brahe and, upon Brahe's unexpected death, replaced him as imperial mathematician of Emperor Rudolph II. He was then able to use Brahe's extensive observations to make remarkable breakthroughs in astronomy, such as the three laws of planetary motion. Kepler would not have been able to produce his laws without the observations of Tycho, because they allowed Kepler to prove that planets traveled in ellipses, and that the Sun does not sit directly in the center of an orbit but at a focus. Galileo Galilei came after Kepler and developed his own telescope with enough magnification to allow him to study Venus and discover that it has phases like a moon. The discovery of the phases of Venus was one of the more influential reasons for the transition from geocentrism to heliocentrism. [14] Sir Isaac Newton's Philosophiæ Naturalis Principia Mathematica concluded the Copernican Revolution. The development of his laws of planetary motion and universal gravitation explained the presumed motion related to the heavens by asserting a gravitational force of attraction between two objects. [15]
In 1596, Kepler published his first book, the Mysterium Cosmographicum , which was the second (after Thomas Digges, in 1576) to endorse Copernican cosmology by an astronomer since 1540. [12] The book described his model that used Pythagorean mathematics and the five Platonic solids to explain the number of planets, their proportions, and their order. The book garnered enough respect from Tycho Brahe to invite Kepler to Prague and serve as his assistant.
In 1600, Kepler set to work on the orbit of Mars, the second most eccentric of the six planets known at that time. This work was the basis of his next book, the Astronomia nova , which he published in 1609. The book argued heliocentrism and ellipses for planetary orbits instead of circles modified by epicycles. This book contains the first two of his eponymous three laws of planetary motion. In 1619, Kepler published his third and final law which showed the relationship between two planets instead of single planet movement.[ citation needed ]
Kepler's work in astronomy was new in part. Unlike those who came before him, he discarded the assumption that planets moved in a uniform circular motion, replacing it with elliptical motion. Also, like Copernicus, he asserted the physical reality of a heliocentric model as opposed to a geocentric one. Yet, despite all of his breakthroughs, Kepler could not explain the physics that would keep a planet in its elliptical orbit.
Galileo Galilei was an Italian scientist who is sometimes referred to as the "father of modern observational astronomy". [16] His improvements to the telescope, astronomical observations, and support for Copernicanism were all integral to the Copernican Revolution.
Based on the designs of Hans Lippershey, Galileo designed his own telescope which, in the following year, he had improved to 30x magnification. [17] Using this new instrument, Galileo made a number of astronomical observations which he published in the Sidereus Nuncius in 1610. In this book, he described the surface of the Moon as rough, uneven, and imperfect. He also noted that "the boundary dividing the bright from the dark part does not form a uniformly oval line, as would happen in a perfectly spherical solid, but is marked by an uneven, rough, and very sinuous line, as the figure shows." [18] These observations challenged Aristotle's claim that the Moon was a perfect sphere and the larger idea that the heavens were perfect and unchanging.
Galileo's next astronomical discovery would prove to be a surprising one. While observing Jupiter over the course of several days, he noticed four stars close to Jupiter whose positions were changing in a way that would be impossible if they were fixed stars. After much observation, he concluded these four stars were orbiting the planet Jupiter and were in fact moons, not stars. [19] This was a radical discovery because, according to Aristotelian cosmology, all heavenly bodies revolve around the Earth and a planet with moons obviously contradicted that popular belief. [20] While contradicting Aristotelian belief, it supported Copernican cosmology which stated that Earth is a planet like all others. [21]
In 1610, Galileo observed that Venus had a full set of phases, similar to the phases of the moon we can observe from Earth. This was explainable by the Copernican or Tychonic systems which said that all phases of Venus would be visible due to the nature of its orbit around the Sun, unlike the Ptolemaic system which stated only some of Venus's phases would be visible. Due to Galileo's observations of Venus, Ptolemy's system became highly suspect and the majority of leading astronomers subsequently converted to various heliocentric models, making his discovery one of the most influential in the transition from geocentrism to heliocentrism. [14]
In the sixteenth century, a number of writers inspired by Copernicus, such as Thomas Digges, [22] Giordano Bruno [23] and William Gilbert [24] argued for an indefinitely extended or even infinite universe, with other stars as distant suns. This contrasts with the Aristotelian view of a sphere of the fixed stars. Although opposed by Copernicus and (initially) Kepler, in 1610 Galileo made his telescopic observation of the faint strip of the Milky Way, which he found it resolves in innumerable white star-like spots, presumably farther stars themselves. [25] By the middle of the 17th century this new view became widely accepted, partly due to the support of René Descartes.
Newton was a well known English physicist and mathematician who was known for his book Philosophiæ Naturalis Principia Mathematica . [26] He was a main figure in the Scientific Revolution for his laws of motion and universal gravitation. The laws of Newton are said to be the ending point of the Copernican Revolution.[ by whom? ]
Newton used Kepler's laws of planetary motion to derive his law of universal gravitation. Newton's law of universal gravitation was the first law he developed and proposed in his book Principia. The law states that any two objects exert a gravitational force of attraction on each other. The magnitude of the force is proportional to the product of the gravitational masses of the objects, and inversely proportional to the square of the distance between them. [15] Along with Newton's law of universal gravitation, the Principia also presents his three laws of motion. These three laws explain inertia, acceleration, action and reaction when a net force is applied to an object.
Immanuel Kant in his Critique of Pure Reason (1787 edition) drew a parallel between the "Copernican revolution" and the epistemology of his new transcendental philosophy. [27] Kant's comparison is made in the Preface to the second edition of the Critique of Pure Reason (published in 1787; a heavy revision of the first edition of 1781). Kant argues that, just as Copernicus moved from the supposition of heavenly bodies revolving around a stationary spectator to a moving spectator, so metaphysics, "proceeding precisely on the lines of Copernicus' primary hypothesis", should move from assuming that "knowledge must conform to objects" to the supposition that "objects must conform to our [ a priori ] knowledge". [lower-alpha 2]
Much has been said on what Kant meant by referring to his philosophy as "proceeding precisely on the lines of Copernicus' primary hypothesis". There has been a long-standing discussion on the appropriateness of Kant's analogy because, as most commentators see it, Kant inverted Copernicus' primary move. [29] According to Tom Rockmore, [30] Kant himself never used the "Copernican revolution" phrase about himself, though it was "routinely" applied to his work by others.
Following Kant, the phrase "Copernican Revolution" in the 20th century came to be used for any (supposed) paradigm shift, for example in reference to Freudian psychoanalysis [31] or continental philosophy and analytic linguistic philosophy. [32]
Johannes Kepler was a German astronomer, mathematician, astrologer, natural philosopher and writer on music. He is a key figure in the 17th-century Scientific Revolution, best known for his laws of planetary motion, and his books Astronomia nova, Harmonice Mundi, and Epitome Astronomiae Copernicanae, influencing among others Isaac Newton, providing one of the foundations for his theory of universal gravitation. The variety and impact of his work made Kepler one of the founders and fathers of modern astronomy, the scientific method, natural and modern science. He has been described as the "father of science fiction" for his novel Somnium.
Tycho Brahe, generally called Tycho for short, was a Danish astronomer of the Renaissance, known for his comprehensive and unprecedentedly accurate astronomical observations. He was known during his lifetime as an astronomer, astrologer, and alchemist. He was the last major astronomer before the invention of the telescope. Tycho Brahe has also been described as the greatest pre-telescopic astronomer.
In astronomy, the geocentric model is a superseded description of the Universe with Earth at the center. Under most geocentric models, the Sun, Moon, stars, and planets all orbit Earth. The geocentric model was the predominant description of the cosmos in many European ancient civilizations, such as those of Aristotle in Classical Greece and Ptolemy in Roman Egypt, as well as during the Islamic Golden Age.
In the Hipparchian, Ptolemaic, and Copernican systems of astronomy, the epicycle was a geometric model used to explain the variations in speed and direction of the apparent motion of the Moon, Sun, and planets. In particular it explained the apparent retrograde motion of the five planets known at the time. Secondarily, it also explained changes in the apparent distances of the planets from the Earth.
Heliocentrism is a superseded astronomical model in which the Earth and planets revolve around the Sun at the center of the universe. Historically, heliocentrism was opposed to geocentrism, which placed the Earth at the center. The notion that the Earth revolves around the Sun had been proposed as early as the third century BC by Aristarchus of Samos, who had been influenced by a concept presented by Philolaus of Croton. In the 5th century BC the Greek Philosophers Philolaus and Hicetas had the thought on different occasions that the Earth was spherical and revolving around a "mystical" central fire, and that this fire regulated the universe. In medieval Europe, however, Aristarchus' heliocentrism attracted little attention—possibly because of the loss of scientific works of the Hellenistic period.
The Tychonic system is a model of the universe published by Tycho Brahe in 1588, which combines what he saw as the mathematical benefits of the Copernican system with the philosophical and "physical" benefits of the Ptolemaic system. The model may have been inspired by Valentin Naboth and Paul Wittich, a Silesian mathematician and astronomer. A similar cosmological model was independently proposed in the Hindu astronomical treatise Tantrasamgraha by Nilakantha Somayaji of the Kerala school of astronomy and mathematics.
The celestial spheres, or celestial orbs, were the fundamental entities of the cosmological models developed by Plato, Eudoxus, Aristotle, Ptolemy, Copernicus, and others. In these celestial models, the apparent motions of the fixed stars and planets are accounted for by treating them as embedded in rotating spheres made of an aetherial, transparent fifth element (quintessence), like gems set in orbs. Since it was believed that the fixed stars did not change their positions relative to one another, it was argued that they must be on the surface of a single starry sphere.
Equant is a mathematical concept developed by Claudius Ptolemy in the 2nd century AD to account for the observed motion of the planets. The equant is used to explain the observed speed change in different stages of the planetary orbit. This planetary concept allowed Ptolemy to keep the theory of uniform circular motion alive by stating that the path of heavenly bodies was uniform around one point and circular around another point.
In astronomy, the fixed stars are the luminary points, mainly stars, that appear not to move relative to one another against the darkness of the night sky in the background. This is in contrast to those lights visible to naked eye, namely planets and comets, that appear to move slowly among those "fixed" stars.
Giovanni Battista Riccioli, SJ was an Italian astronomer and a Catholic priest in the Jesuit order. He is known, among other things, for his experiments with pendulums and with falling bodies, for his discussion of 126 arguments concerning the motion of the Earth, and for introducing the current scheme of lunar nomenclature. He is also widely known for discovering the first double star. He argued that the rotation of the Earth should reveal itself because on a rotating Earth, the ground moves at different speeds at different times.
Astronomia nova is a book, published in 1609, that contains the results of the astronomer Johannes Kepler's ten-year-long investigation of the motion of Mars.
Michael Maestlin was a German astronomer and mathematician, known for being the mentor of Johannes Kepler. He was a student of Philipp Apian and was known as the teacher who most influenced Kepler. Maestlin was considered to be one of the most significant astronomers between the time of Copernicus and Kepler.
Mysterium Cosmographicum is an astronomy book by the German astronomer Johannes Kepler, published at Tübingen in late 1596 and in a second edition in 1621. Kepler proposed that the distance relationships between the six planets known at that time could be understood in terms of the five Platonic solids, enclosed within a sphere that represented the orbit of Saturn.
Copernican heliocentrism is the astronomical model developed by Nicolaus Copernicus and published in 1543. This model positioned the Sun at the center of the Universe, motionless, with Earth and the other planets orbiting around it in circular paths, modified by epicycles, and at uniform speeds. The Copernican model displaced the geocentric model of Ptolemy that had prevailed for centuries, which had placed Earth at the center of the Universe.
Paul Wittich was a German mathematician and astronomer whose Capellan geoheliocentric model, in which the inner planets Mercury and Venus orbit the Sun but the outer planets Mars, Jupiter and Saturn orbit the Earth, may have directly inspired Tycho Brahe's more radically heliocentric geoheliocentric model in which all the 5 known primary planets orbited the Sun, which in turn orbited the stationary Earth.
The center of the Universe is a concept that lacks a coherent definition in modern astronomy; according to standard cosmological theories on the shape of the universe, it has no distinct spatial center.
Historical models of the Solar System first appeared during prehistoric periods and are being updated to this day. The models of the Solar System throughout history were first represented in the early form of cave markings and drawings, calendars and astronomical symbols. Then books and written records became the main source of information that expressed the way the people of the time thought of the Solar System.
The Vicarious Hypothesis, or hypothesis vicaria, was a planetary hypothesis proposed by Johannes Kepler to describe the motion of Mars. The hypothesis adopted the circular orbit and equant of Ptolemy's planetary model as well as the heliocentrism of the Copernican model. Calculations using the Vicarious Hypothesis did not support a circular orbit for Mars, leading Kepler to propose elliptical orbits as one of three laws of planetary motion in Astronomia Nova.
The Wittenberg Interpretation refers to the work of astronomers and mathematicians at the University of Wittenberg in response to the heliocentric model of the Solar System proposed by Nicholas Copernicus, in his 1543 book De revolutionibus orbium coelestium. The Wittenberg Interpretation fostered an acceptance of the heliocentric model and had a part in beginning the Scientific Revolution.
The existence of extraterrestrial life is a scientific idea that has been debated for centuries. Initially, the question was purely speculative; in modern times a limited amount of scientific evidence provides some answers. The idea was first proposed in Ancient Greece, where it was supported by atomists and rejected by Aristotelians. The debate continued during the Middle Ages, when the discussion centered upon whether the notion of extraterrestrial life was compatible with the doctrines of Christianity. The Copernican Revolution radically altered mankind's image of the architecture of the cosmos by removing Earth from the center of the universe, which made the concept of extraterrestrial life more plausible. Today we have no conclusive evidence of extraterrestrial life, but experts in many different disciplines gather to study the idea under the scientific umbrella of astrobiology.
The Puritan Thomas Digges (1546–1595?) was the earliest Englishman to offer a defense of the Copernican theory. ... Accompanying Digges's account is a diagram of the universe portraying the heliocentric system surrounded by the orb of fixed stars, described by Digges as infinitely extended in all dimensions.