Nicolaus Copernicus

On February 19, 1473, Nicolaus Copernicus entered a world that was considered to be the center of the universe. By the time he died in 1543, he had succeeded in changing our views of Earth's place in the cosmos.

Copernicus was a well-educated man, studying first in Poland and then in Bologna, Italy. He then moved to Padua,where he undertook medical studies, and then focused on law at the University of Ferrara. 

He received a doctorate in canon law in 1503. 

Soon afterward, he returned to Poland, spending several years with his uncle, assisting in the administration of the diocese and in the conflict against the Teutonic Knights. During this time, he published his first book, which was a Latin translation of letters on morals by 7th-century Byzantine writer, Theophylactus of Simocatta.

While studying in Bologna, Copernicus was greatly influenced by professor of astronomy Domenico Maria de Ferrara, Copernicus was especially interested in Ferrara's criticism of the “Geography” of Ptolemy. On March 9, 1497 the men observed the occultation (eclipse by the moon) of the star Aldebaran (in the constellation Taurus). In 1500, Nicolaus lectured on astronomy in Rome. So, it should have been no surprise that while performing his ecclesiastical duties and practicing medicine, he also returned his attention to astronomy.

Copernicus wrote a short astronomical treatise, De Hypothesibus Motuum Coelestium a se Constitutis Commentariolus (known as the Commentariolus). In this work he laid down the principles of his new heliocentric astronomy.

Essentially, this was an outline of his later-developed ideas about Earth and its position in the solar system and universe. In it, he suggested that Earth was NOT the center of the cosmos, but that it orbited the Sun. This was not a widely held belief at the time, and the treatise almost disappeared.

A copy of his manuscript was found and published in the 19th century.

In this early writing Copernicus suggested seven ideas about objects in the sky:  

• celestial bodies do not all orbit a central point in the sky;
• the Moon orbits Earth;
• the planets all orbit the Sun (which he thought might be the center of the universe);
• the distance between the Sun and Earth is a very small fraction of the distance from the Sun to the stars. Thus, he thought that parallax is not observed in the stars;
• the apparent motion of the stars stems from the fact that Earth rotates on its axis:
• Earth orbits the Sun, which explains the apparent annual motion of the Sun;
• Earth's orbit around the Sun sometimes make it look as if some planets are moving backwards. 

Not all of these precepts are true or completely accurate, particularly the one about the Sun being the center of the universe. However, Copernicus was at least applying scientific analysis to understanding the motions of distant objects.

In this same period, Copernicus took part in the Fifth Lateran Council's commission on calendar reform in 1515.He also wrote a treatise on monetary reform, and shortly thereafter, began his major work, De Revolutionibus Orbium Coelestium (On the Revolutions of the Celestial Spheres).

Expanding vastly on his earlier work, the Commentariolus, this second book was in direct opposition to Aristotle and to the 2d-century astronomer Ptolemy. Instead of the geocentric system based Ptolemaic model that was approved of by the Church, Copernicus proposed that a rotating Earth revolving with the other planets about a stationary central Sun provided a much simpler explanation for the same observed phenomena of the daily rotation of the heavens, the annual movement of the Sun through the ecliptic, and the periodic retrograde motion of the planets.

Although completed by 1530, De Revolutionibus Orbium Coelestium was first published by a Lutheran printer in Nürnberg, Germany in 1543. It changed the way people looked at Earth's position in the universe forever and influenced later astronomers in their studies of the heavens. One often-repeated Copernican legend claims that he received a printed copy of his treatise on his deathbed. Nicolaus Copernicus died on May 24, 1543.