Nicolaus Copernicus
Nicolaus Copernicus (Polish name: Mikołaj Kopernik) was a sixteenth century astronomer and founder of the heliocentric system, a planetary system with the sun and not the earth in the center.
Nicolaus was born in Toruń on 19 Februari 1473 and died in Frombork on 24 May 1543. The cities of birth and death of Copernicus are now Polish, but were German speaking during the days of Copernicus. In German the cities are called Thorn en Frauenburg. For the largest part of his life Copernicus worked and lived in Frombork, in the east of Poland at the Baltic Sea. This city is the seat of the diocese Warnia (in German Ermland). Although Copernicus was not ordained, he made his living as canon of this diocese and lived the life of a Roman Catholic priest.
At an early age Nicolaus showed much affection for astronomy, yet he made the sensible choice of studying law and medicine, two professions that obviously gave him a greater chance of finding a decent job than astronomy would. After three years of study (1491–1494), he received a bachelor's degree at the Jagiellonian University in Cracow and then went on to earn two master's degrees in Italy, one in Bologna and one in Padua. Copernicus stayed in Italy from 1496 until about 1503. He received a doctorate in canonical law at the university of Ferrara in 1503.
It is likely that Copernicus, during his stay in Italy, got acquainted with the heliocentric model of Aristarchus (ca. 310–230 BC). There is an early (1514) manuscript of Copernicus in which he posits that the earth orbits the sun in one year time and that the retrograde motions of the planets are only apparent, that is, are caused by observation from a moving earth. Further he assumed that the phenomena of sunset and sunrise are caused by a rotation of the earth around its own axis. In brief, Copernicus assumed that the earth does not take a special position in the cosmos, but is just one of the six planets that orbit the sun (the discoveries of Uranus and Neptune were a few hundred years later). The same point of view caused a historic conflict between Galileo Galilei and the Roman Catholic church, almost a century later, because the church believed that the Bible claims a special place for the earth in the universe.
The remaining part of his life Copernicus worked on the quantitative founding of his qualitative ideas of 1514. However, because he could not free himself from the Aristotelian idea that the planetary orbits must be perfect, that is, circles, his astronomical predictions were not much more accurate than those of Ptolemy. Only after Johannes Kepler had unchained himself from the medieval awe for Aristotle, and assumed elliptic orbits, it became possible to surpass the accuracy of Ptolemy. Near the end of his life Copernicus could bring himself finally to publish his results. This decisison was taken under much pressure of his young admirer Rheticus, who believed strongly in Copernicus' ideas. Copernicus' results were expounded in a book, De revolutionibus orbium coelestium (about the revolution of the celestial orbits). Copernicus saw the first printed edition shortly before he died in 1543.
It sometimes stated that Copernicus work initiated a scientific revolution, be that as it may, in any case his work was the start of a revolution in astronomical thought. It must be stressed here that Copernicus did not replace the flat earth by a round earth, as is very often stated. The fact that the earth is a sphere was generally known among the literate since Hellenistic times (about 300 BC). It is perhaps no coincidence that Copernicus' revolution occurred in the first half of sixteenth century, because this was a time of many great changes: The fall of the Byzantine empire (1453), the discovery of the Americas (1492), the 95 theses of Luther on the church door of Wittenberg (1517), the coronation (1519) of Charles V to Holy Roman Emperor, etc.