Copernicus (11/5)

Katie, Robb, Dave, Shawn, Jamie

ABOUT: Nick Copernicus

Nicolaus Copernicus (1473–1543) was a mathematician and astronomer who proposed that the sun was stationary in the center of the universe and the earth revolved around it. Disturbed by the failure of Ptolemy's geocentric model of the universe to follow Aristotle's requirement for the uniform circular motion of all celestial bodies and determined to eliminate Ptolemy's equant, an imaginary point around which the bodies seemed to follow that requirement, Copernicus decided that he could achieve his goal only through a heliocentric model. He thereby created a concept of a universe in which the distances of the planets from the sun bore a direct relationship to the size of their orbits. At the time Copernicus's heliocentric idea was very controversial; nevertheless, it was the start of a change in the way the world was viewed, and Copernicus came to be seen as the initiator of the Scientific Revolution.

Nicolaus Copernicus was born on 19 February 1473, the youngest of four children of Nicolaus Copernicus, Sr., a well-to-do merchant who had moved to Torun from Cracow, and Barbara Watzenrode, the daughter of a leading merchant family in Torun. The city, on the Vistula River, had been an important inland port in the Hanseatic League. However, fighting between the Order of the Teutonic Knights and the Prussian Union in alliance with the Kingdom of Poland ended in 1466, and West Prussia, which included Torun, was ceded to Poland, and Torun was declared a free city of the Polish kingdom. Thus the child of a German family was a subject of the Polish crown.

The father died in 1483, and the children's maternal uncle, Lucas Watzenrode (1447–1512), took them under his protection. Watzenrode was a very successful cleric — he was to become bishop of Warmia (Ermland in German) in 1489 — and he both facilitated his nephew's advancement in the church and directed his education. In 1491 Copernicus enrolled in the University of Cracow. There is no record of his having obtained a degree, which was not unusual at the time as he did not need a bachelor's degree for his ecclesiastical career or even to study for a higher degree. But the University of Cracow offered courses in mathematics, astronomy, and astrology (see Goddu 25–33 on all the university offerings), and Copernicus's interest was sparked, which is attested to by his acquisition of books in these subjects while at Cracow.^[1]

In 1495 Watzenrode arranged Copernicus's election as canon of the chapter of Frombork (Frauenberg in German) of the Cathedral Chapter of Warmia, an administrative position just below that of bishop. He assumed the post two years later, and his financial situation was secure for life. In the meantime, following in his uncle's footsteps, Copernicus went to the University of Bologna in 1496 to study canon law (see Goddu part 2 on what Copernicus may have encountered in Italy). While at Bologna he lived with the astronomy professor Domenico Maria Novara and made his first astronomical observations. In addition, as Rosen (1971, 323) noted, “In establishing close contact with Novara, Copernicus met, perhaps for the first time in his life, a mind that dared to challenge the authority of [Ptolemy] the most eminent ancient writer in his chosen fields of study.” Copernicus also gave a lecture on mathematics in Rome, which may have focused on astronomy.

His Astronomy:

Classical astronomy followed principles established by Aristotle. Aristotle accepted the idea that there were four physical elements — earth, water, air, and fire. He put the earth in the center of the universe and contended that these elements were below the moon, which was the closest celestial body. There were seven planets, or wandering stars, because they had a course through the zodiac in addition to traveling around the earth: the moon, Mercury, Venus, the sun, Mars, Jupiter. Beyond that were the fixed stars. The physical elements, according to Aristotle moved vertically, depending on their ‘heaviness’ or ‘gravity’; the celestial bodies were not physical but a ‘fifth element’ or ‘quintessence’ whose nature was to move in perfect circles around the earth, making a daily rotation. Aristotle envisioned the earth as the true center of all the circles or ‘orbs’ carrying the heavenly bodies around it and all motion as ‘uniform,’ that is, unchanging.
But observers realized that the heavenly bodies did not move as Aristotle postulated. The earth was not the true center of the orbits and the motion was not uniform. The most obvious problem was that the outer planets seemed to stop, move backwards in ‘retrograde’ motion for a while, and then continue forwards. By the second century, when Ptolemy compiled hisAlmagest (this common name of Ptolemy's Syntaxis was derived from its Arabic title), astronomers had developed the concept that the orbit moves in ‘epicycles’ around a ‘deferrent,’ that is, they move like a flat heliacal coil around a circle around the earth. The earth was also off-center, on an ‘eccentric,’ as the heavenly bodies moved around a central point. Ptolemy added a point on a straight line opposite the eccentric, which is called the ‘equalizing point’ or the ‘equant,’ and around this point the heavenly bodies moved uniformly. Moreover, unlike the Aristotelian model, Ptolemy's Almagest did not describe a unified universe. The ancient astronomers who followed Ptolemy, however, were not concerned if his system did not describe the ‘true’ motions of the heavenly bodies; their concern was to ‘save the phenomena,’ that is, give a close approximation of where the heavenly bodies would be at a given point in time. And in an age without professional astronomers, let alone the telescope, Ptolemy did a good job plotting the courses of the heavenly bodies.

Not all Greek astronomical ideas followed this geocentric system. Pythagoreans suggested that the earth moved around a central fire (not the sun). Archimedes wrote that Aristarchus of Samos actually proposed that the earth rotated daily and revolved around the sun.