Nicolaus Copernicus

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Nicolaus Copernicus : biography

19 February 1473 – 24 May 1543

"1. There is no one center of all the celestial circles or spheres. 2. The center of the earth is not the center of the universe, but only of gravity and of the lunar sphere. 3. All the spheres revolve about the sun as their mid-point, and therefore the sun is the center of the universe. 4. The ratio of the earth’s distance from the sun to the height of the firmament (outermost celestial sphere containing the stars) is so much smaller than the ratio of the earth’s radius to its distance from the sun that the distance from the earth to the sun is imperceptible in comparison with the height of the firmament. 5. Whatever motion appears in the firmament arises not from any motion of the firmament, but from the earth’s motion. The earth together with its circumjacent elements performs a complete rotation on its fixed poles in a daily motion, while the firmament and highest heaven abide unchanged. 6. What appear to us as motions of the sun arise not from its motion but from the motion of the earth and our sphere, with which we revolve about the sun like any other planet. The earth has, then, more than one motion. 7. The apparent retrograde and direct motion of the planets arises not from their motion but from the earth’s. The motion of the earth alone, therefore, suffices to explain so many apparent inequalities in the heavens."

De revolutionibus itself was divided into six parts, called "books":

  1. General vision of the heliocentric theory, and a summarized exposition of his idea of the World
  2. Mainly theoretical, presents the principles of spherical astronomy and a list of stars (as a basis for the arguments developed in the subsequent books)
  3. Mainly dedicated to the apparent motions of the Sun and to related phenomena
  4. Description of the Moon and its orbital motions
  5. Exposition of the motions in longitude of the non-terrestrial planets
  6. Exposition of the motions in latitude of the non-terrestrial planets

Successors

Georg Joachim Rheticus could have been Copernicus’ successor, but did not rise to the occasion. Erasmus Reinhold could have been his successor, but died prematurely. The first of the great successors was Tycho Brahe (though he did not think the earth orbited the sun), followed by Johannes Kepler, who had worked as Tycho’s assistant in Prague.

Despite the near universal acceptance today of the basic heliocentric idea (though not the epicycles or the circular orbits), Copernicus’ theory was originally slow to catch on. Scholars hold that sixty years after the publication of The Revolutions there were only around 15 astronomers espousing Copernicanism in all of Europe, "Thomas Digges and Thomas Hariot in England; Giordano Bruno and Galileo Galilei in Italy; Diego de Zuniga in Spain; Simon Stevin in the Low Countries; and in Germany, the largest group – Georg Joachim Rheticus, Michael Maestlin, Christoph Rothmann (who may have later recanted), and Johannes Kepler." Additional possibilities are Englishman William Gilbert, along with Achilles Gasser, Georg Vogelin, Valentin Otto, and Tiedemann Giese.

Arthur Koestler, in his popular book The Sleepwalkers, asserted that Copernicus’ book had not been widely read on its first publication. This claim was trenchantly criticised by Edward Rosen, and has been decisively disproved by Owen Gingerich, who examined every surviving copy of the first two editions and found copious marginal notes by their owners throughout many of them. Gingerich published his conclusions in 2004 in The Book Nobody Read.

The intellectual climate of the time "remained dominated by Aristotelian philosophy and the corresponding Ptolemaic astronomy. At that time there was no reason to accept the Copernican theory, except for its mathematical simplicity [by avoiding using the equant in determining planetary positions]." Tycho Brahe’s system ("that the earth is stationary, the sun revolves about the earth, and the other planets revolve about the sun") also directly competed with Copernicus’. It was only a half century later with the work of Kepler and Galileo that any substantial evidence defending Copernicanism appeared, starting "from the time when Galileo formulated the principle of inertia…[which] helped to explain why everything would not fall off the earth if it were in motion." It was not until "after Isaac Newton formulated the universal law of gravitation and the laws of mechanics [in his 1687 Principia], which unified terrestrial and celestial mechanics, was the heliocentric view generally accepted."