Copernican Revolution

Copernican Revolution

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The Copernican Revolution refers to the paradigm shift
Paradigm shift
A Paradigm shift is, according to Thomas Kuhn in his influential book The Structure of Scientific Revolutions , a change in the basic assumptions, or paradigms, within the ruling theory of science...

 away from the Ptolemaic model of the heavens, which postulated the Earth
Earth is the third planet from the Sun, and the densest and fifth-largest of the eight planets in the Solar System. It is also the largest of the Solar System's four terrestrial planets...

 at the center of the galaxy
A galaxy is a massive, gravitationally bound system that consists of stars and stellar remnants, an interstellar medium of gas and dust, and an important but poorly understood component tentatively dubbed dark matter. The word galaxy is derived from the Greek galaxias , literally "milky", a...

, towards the heliocentric model
Copernican heliocentrism
Copernican heliocentrism is the name given to the astronomical model developed by Nicolaus Copernicus and published in 1543. It positioned the Sun near the center of the Universe, motionless, with Earth and the other planets rotating around it in circular paths modified by epicycles and at uniform...

 with the Sun
The Sun is the star at the center of the Solar System. It is almost perfectly spherical and consists of hot plasma interwoven with magnetic fields...

 at the center of our Solar System. It was one of the starting points of the Scientific Revolution
Scientific revolution
The Scientific Revolution is an era associated primarily with the 16th and 17th centuries during which new ideas and knowledge in physics, astronomy, biology, medicine and chemistry transformed medieval and ancient views of nature and laid the foundations for modern science...

 of the 16th century.

Historical overview

In 1543 Nicolaus Copernicus
Nicolaus Copernicus
Nicolaus Copernicus was a Renaissance astronomer and the first person to formulate a comprehensive heliocentric cosmology which displaced the Earth from the center of the universe....

 published his treatise De revolutionibus orbium coelestium
De revolutionibus orbium coelestium
De revolutionibus orbium coelestium is the seminal work on the heliocentric theory of the Renaissance astronomer Nicolaus Copernicus...

(On the Revolutions of the Heavenly Spheres), which presented a heliocentric model view of the universe. It took about 200 years for a heliocentric model to replace the Ptolemaic model.

To describe the innovation initiated by Copernicus as the simple interchange of the position of the earth and sun is to make a molehill out of a promontory in the development of human thought. If Copernicus' proposal had had no consequences outside astronomy, it would have been neither so long delayed nor so strenuously resisted.

Nicolaus Copernicus

Nicolaus Copernicus
Nicolaus Copernicus
Nicolaus Copernicus was a Renaissance astronomer and the first person to formulate a comprehensive heliocentric cosmology which displaced the Earth from the center of the universe....

, in his On the Revolutions of the Heavenly Spheres (1543), demonstrated that the motion of the heavens can be explained without the Earth being in the geometric center of the system. This led to the view that we can dispense with the assumption that we are observing the universe from a special position. Although Copernicus initiated the revolution, he certainly didn't complete it. He continued to believe in the celestial spheres
Celestial spheres
The celestial spheres, or celestial orbs, were the fundamental entities of the cosmological models developed by Plato, Eudoxus, Aristotle, Ptolemy, Copernicus and others...

 and could provide little in the way of direct observational evidence that his theory was superior to Ptolemy's.

Tycho Brahe

The Danish astronomer Tycho Brahe
Tycho Brahe
Tycho Brahe , born Tyge Ottesen Brahe, was a Danish nobleman known for his accurate and comprehensive astronomical and planetary observations...

, while remaining a geocentric, contributed to the revolution by showing that the heavenly spheres were at best mathematical devices rather than physical objects, since the great comet of 1577 passed through the spheres of several planets, and, moreover, the spheres of Mars and the Sun passed through each other. Brahe and his assistants also made the numerous and painstaking observations which allowed Johannes Kepler
Johannes Kepler
Johannes Kepler was a German mathematician, astronomer and astrologer. A key figure in the 17th century scientific revolution, he is best known for his eponymous laws of planetary motion, codified by later astronomers, based on his works Astronomia nova, Harmonices Mundi, and Epitome of Copernican...

 to derive his laws of planetary motion. Kepler's revised heliocentric system gave a far more accurate description of planetary motions than the Ptolemaic one.

Johannes Kepler

Johannes Kepler
Johannes Kepler
Johannes Kepler was a German mathematician, astronomer and astrologer. A key figure in the 17th century scientific revolution, he is best known for his eponymous laws of planetary motion, codified by later astronomers, based on his works Astronomia nova, Harmonices Mundi, and Epitome of Copernican...

 proposed an alternative model, essentially the modern one, in which the planetary orbits were ellipses, rather than circles modified by epicycles as Copernicus used.

Galileo Galilei

Starting with his first use of the telescope for astronomical observations in 1610, Galileo Galilei
Galileo Galilei
Galileo Galilei , was an Italian physicist, mathematician, astronomer, and philosopher who played a major role in the Scientific Revolution. His achievements include improvements to the telescope and consequent astronomical observations and support for Copernicanism...

 provided support for the Copernican system by observing the phases of Venus
Phases of Venus
The phases of the planet Venus are the different variations of lighting seen on the planet's surface, similar to lunar phases. The first recorded observations of them were telescopic observations by Galileo Galilei in 1610...

 and the moons of Jupiter (which showed that the apparently anomalous orbit of the Moon in Copernicus' theory was not unique). Galileo also wrote a defense of the heliocentric system, Dialogue Concerning the Two Chief World Systems
Dialogue Concerning the Two Chief World Systems
The Dialogue Concerning the Two Chief World Systems was a 1632 Italian language book by Galileo Galilei comparing the Copernican system with the traditional Ptolemaic system. It was translated to Latin as Systema cosmicum in 1635 by Matthias Bernegger...

(1632), which led to his trial
Galileo affair
The Galileo affair was a sequence of events, beginning around 1610, during which Galileo Galilei came into conflict with the Aristotelian scientific view of the universe , over his support of Copernican astronomy....

 and house arrest by the Inquisition
The Inquisition, Inquisitio Haereticae Pravitatis , was the "fight against heretics" by several institutions within the justice-system of the Roman Catholic Church. It started in the 12th century, with the introduction of torture in the persecution of heresy...


Giordano Bruno

In the same period, a number of writers inspired by Copernicus, such as Thomas Digges
Thomas Digges
Sir Thomas Digges was an English mathematician and astronomer. He was the first to expound the Copernican system in English but discarded the notion of a fixed shell of immoveable stars to postulate infinitely many stars at varying distances; he was also first to postulate the "dark night sky...

 and Giordano Bruno
Giordano Bruno
Giordano Bruno , born Filippo Bruno, was an Italian Dominican friar, philosopher, mathematician and astronomer. His cosmological theories went beyond the Copernican model in proposing that the Sun was essentially a star, and moreover, that the universe contained an infinite number of inhabited...

, argued for an infinite or at least indefinitely extended universe, with other stars as distant suns. Although opposed by Copernicus and Kepler (with Galileo agnostic), by the middle of the 17th century this became widely accepted, partly due to the support of René Descartes
René Descartes
René Descartes ; was a French philosopher and writer who spent most of his adult life in the Dutch Republic. He has been dubbed the 'Father of Modern Philosophy', and much subsequent Western philosophy is a response to his writings, which are studied closely to this day...


Isaac Newton

The Copernican revolution was arguably completed by Isaac Newton
Isaac Newton
Sir Isaac Newton PRS was an English physicist, mathematician, astronomer, natural philosopher, alchemist, and theologian, who has been "considered by many to be the greatest and most influential scientist who ever lived."...

 whose Philosophiae Naturalis Principia Mathematica
Philosophiae Naturalis Principia Mathematica
Philosophiæ Naturalis Principia Mathematica, Latin for "Mathematical Principles of Natural Philosophy", often referred to as simply the Principia, is a work in three books by Sir Isaac Newton, first published 5 July 1687. Newton also published two further editions, in 1713 and 1726...

(1687) provided a consistent physical explanation which showed that the planets are kept in their orbits by the familiar force of gravity. Newton was able to derive Kepler's laws as good approximations and to get yet more accurate predictions by taking account of the gravitational interaction between the planets.

Metaphorical use

The philosopher Immanuel Kant
Immanuel Kant
Immanuel Kant was a German philosopher from Königsberg , researching, lecturing and writing on philosophy and anthropology at the end of the 18th Century Enlightenment....

 made an analogy to Copernicus when describing a problem from a different point of view, and some later philosophers have called it his "Copernican revolution". The conditions and qualities he ascribed to the subject
Subject (philosophy)
In philosophy, a subject is a being that has subjective experiences, subjective consciousness or a relationship with another entity . A subject is an observer and an object is a thing observed...

 of knowledge
Knowledge is a familiarity with someone or something unknown, which can include information, facts, descriptions, or skills acquired through experience or education. It can refer to the theoretical or practical understanding of a subject...

 placed man at the centre of all conceptual and empirical experience, and overcame the rationalism
In epistemology and in its modern sense, rationalism is "any view appealing to reason as a source of knowledge or justification" . In more technical terms, it is a method or a theory "in which the criterion of the truth is not sensory but intellectual and deductive"...

Empiricism is a theory of knowledge that asserts that knowledge comes only or primarily via sensory experience. One of several views of epistemology, the study of human knowledge, along with rationalism, idealism and historicism, empiricism emphasizes the role of experience and evidence,...

 impasse, characteristic of the 17th and 18th centuries. See also Subject-object problem
Subject-object problem
The subject–object problem, a longstanding philosophical issue, is concerned with the analysis of human experience, and of what within experience is "subjective" and what is "objective."...