Nicolaus Copernicus, 1473 - 1543, Polish
Astronomer, Mathematician.
Nicolaus was born into a wealthy merchant family and was the youngest of 4 children.
Nicolaus's education was taken over by his uncle after his father died.
The uncle was a Bishop, and he directed young Nicolaus toward the priesthood and had him enrolled at the University of Bologna. While there he became acquainted with the university's astronomer and mathematician who introduced him to the astronomy of Ptolemy, in which the earth is thought to be the center of the universe, known as the geocentric theory.
Young Copernicus
Copernicus was destined for the priesthood, and his topics of study, astrology, and medicine were directed to that end. When he finally graduated with a doctorate in theology, after passing through 3 different universities, his uncle had a position made vacant for him at the Bishop's palace. But first, he needed to take the vows of a canon, which he did, vowing to be celibate, among other vows. His duties involved administrative work, as well as medical assistance for the rest of the staff. Copernicus did not take the final step and become a priest. Instead, he preferred to remain a Canon, which allowed him time to devote himself to his vocation of astronomy and mathematics. His interest was probably sparked by Ptolemy's writings.
Ptolemy and his geocentric world
Ptolemy lived in the second century CE, in the intellectual center of Alexandria, Egypt. His geocentric ideas presented in his book "Almagest" were those that had been developed since the time of Aristotle and were generally accepted by astronomers across Europe and fully supported by Rome. By the time of Copernicus, the hypotheses had survived for about 1400 years.
Ptolemaic planetary hypotheses implied that the planets and the sun moved around the earth and that without a telescope it would be difficult to prove otherwise. Copernicus did not have a telescope, they had not been developed, but he did have lots of data, readings from his astrolabe and sundial.
Subsequently, he found that the Ptolemaic system had "defects", and that it "presented no small difficulties".
In 1514 he presented a handwritten essay setting out his heliocentric proposition. In this proposition, the earth and all the planets revolved around the sun, and not about the earth, making the sun the center of the known universe. Also, the earth rotates about its own axis once every 24 hours.
Copernicus and his heliocentric world
Copernicus was well aware he was treading on dangerous territory, by sending it out, even if only to friends and students who had been contemporary of him. Although it was sent anonymously it was quickly identified and spread rapidly throughout the astronomical community of Europe. The "Larger Work", presenting the data and technical details supporting heliocentric planets, was also promised to be published soon.
The larger work, eventually called "On the Revolutions of the Heavenly Spheres", was not published until the year of his death, 1543, nearly 3 decades after saying it would be published soon.
Copernicus had valid reasons for the delay.
He was employed by the Church and they paid his salary, on which he depended. The difficulty lay in the fact that the Church held to the view that the earth was the center of the world, the universe, and everything in it. The geocentric concept was in line with the doctrine of Rome's theology.
The Inquisition would want to know if one of their own, or anyone else, was promoting a contrary view of the world.
As well, Copernicus was forever making small modifications, additions, and deletions, according to his new findings.
The manuscript was finally published as a consequence of a Lutheran Professor of mathematics at the University of Wittenberg, Joachim Rheticus. Rheticus left his university position and stayed with Copernicus for more than 2 years, helping him to straighten out the mathematics and in general tidy up the presentation into a publishable form. For whatever reason, Copernicus needed to be encouraged to submit his work.
Joachim Rheticus
There was also significant turmoil after it had been first released. The publisher had taken the liberty of adding a foreword to the book.
Copernicus had asked the person responsible for seeing the book through the whole process for any suggestions on how to minimize the consternation that was to be expected. The suggestion was to say that the ideas are just hypotheses. This was rejected.
Nevertheless, this guardian of the publishing process decided he was right. He had a short note added to the front of the book to the effect that this is a hypothesis, and "let no one expect anything certain from astronomy ..... it is not put forward to convince anyone that they are, but merely to provide a reliable basis for computation".
Copernicus became ill, and Rheticus became angry and furious.
At the time of the publication, Copernicus was on his deathbed. Having received a copy of the final version he felt at ease and satisfied enough to lie back and die in peace. It had been a long and hard struggle.
His book started a revolution. The next step was taken by Kepler, defining the planetary orbits with his 3 laws. After that Newton's Universal Gravitation law provided the why.