Is the completion of a book an achievement?

Nicolaus Copernicus

Nicolaus Copernicus lived from 1473 to 1543

The name of Nicolaus Copernicus is inextricably linked with a scientific revolution - with his ideas he overthrew the geocentric worldview of Ptolemy, which had been valid for 1400 years, and brought a heliocentric system into discussion. The earth was separated from the center of the world by him and classified as a simple planet. Your previous position should now be occupied by the sun. From now on he made the planets and the earth revolve around them as the center.

Although we take this for granted today, it took a long time before the new ideas really took hold. The church and many scholars resisted it for a long time and violently. In the end, however, the heliocentric worldview prevailed, which we still call the Copernican system today.

The youth

Nicolaus Copernicus was born as the son of a wealthy merchant in Thorn (Torun) in what is now Poland. When he was ten years old, his father died. So he came into the care of his uncle Lucas Watzenrode. He liked his foster son and took good care of him. He had planned a position in church service for Nikolaus and initially sent him to study. Copernicus attended the university in Cracow, where he learned mathematics and astronomy and then went to Italy to study spiritual and secular law and medicine in Bologna, Padua and Ferrara.

In Italy he lived with an astronomer and learned practical celestial observation from him, until now he had only known astronomy from theory. It is here that his love for the stars kindled. He obtained all available literature on the subject and even learned the Greek language especially to be able to read the astronomical works of the ancient Greeks in the original.

In conversations with other students he learned that Ptolemy's Almagest contained many inaccuracies and inconsistencies. Copernicus decided for himself to look for further mistakes and to make his own observations in order to find out the true course of the stars.

To describe the course of the planets and the moon, Ptolemy had devised a complicated system of circles and auxiliary circles. According to his system for the moon, it would have to appear twice as large at a half moon as at a full moon, which of course is not the case. Above all, the occasional backward movement of the planets in the sky made it difficult to describe their course because there was no good explanation for it.

The complicated epicyclic systems could not reproduce the behavior of the moon and planets in the sky very precisely. Copernicus pondered this and came up with a simple but revolutionary idea.

The conventional geocentric worldview

Copernicus discovered that the problem with the backward movements of the planets could easily be solved if he detached the earth from the center of the world and instead placed the sun in the center. The earth should orbit the sun, just like the planets. Since the orbits are then of different lengths, planets running inside overtake the outside ones.

It would be much better to explain why Mars, Jupiter and Saturn loop in the sky each time they are in opposition, and why they also run backwards. At that moment they are simply overtaken by the earth moving further inwards. From the observation position of the earth they seem to move backwards in the sky.

So far, however, the geocentric world system has appliedwhich was written down by Ptolemy around the year 140. One imagined the earth in the center of the world, and all celestial bodies orbit it, the moon, the sun and the 5 planets known up to then. Ptolemy attached each celestial body to its own crystal bowl. On the very outside, on the 8th bowl, all the stars were attached. Each bowl turned and led the body attached to it around the earth.

Another problem arose with the observational data of Ptolemy, which were already 1400 years old in Copernicus' time. The location of the sun at certain points in time in the course of the year no longer coincided with its actual course. According to Aristotelian doctrine, the starry sky was viewed as unchangeable and eternally valid, but obviously something had shifted here.

Today we know what is behind it, namely the precession, a fluctuation of the earth's axis. It is hardly noticeable in a person's lifetime, but over longer periods of time the shifts of the celestial north pole and the locations of the sun and planets on the ecliptic become clear. This does not fit with the assumption that the earth is immovable and immovable in the center of the universe.


The new ideas of Copernicus

As early as 1514, Copernicus put his ideas down in writing. He wrote a little treatise on it, which he called the Commentariolus, and circulated a few copies of it among friends. Even then, he clearly formulated his innovations:

  • The earth is not the center of the world, only the center of the lunar orbit.
  • All orbit circles surround the sun, so the center of the world is near the sun.
  • The movement of the sky of the fixed stars is caused by the rotation of the earth around itself.
  • The movement of the sun in the sky is not a movement of its own, but is caused by the movement of the earth around the sun and by the rotation of the earth.
  • The loops of the planets in the sky are only apparent movements that arise because the earth also moves and our point of view changes in the process.

After completing his studies, Nikolaus took up the position of Canon of Warmia and was entrusted with the administration of his cathedral district. At the same time, he also worked as a doctor and treated his subordinates for free. He could only do astronomy as a hobby on the side, which he obviously did very intensively. He worked on his theses for over 3 decades and tried to substantiate them with his own observations. To do this, he had a little tower built without a roof, in which he set up his observation instruments and spent many nights there.

During his life he never thought of making his findings known to a broad public. He knew how firmly the old world model was in people's heads and didn't want people to tear up his ideas and make them look ridiculous. Hardly anyone could imagine a moving earth at the time, you don't feel anything of its movement. His contemporaries were of the opinion that when the earth turns, you have to feel the wind. Or that objects would have to fall down at an angle.

Copernicus could not provide any real evidence that he was right about his heliocentric system. The observations can be interpreted in such a way that both the geocentric and the heliocentric model fit. And one look at the sky is enough to convince yourself that everything revolves around the earth and that the earth is fixed ...

It was only when Copernicus got to know Rheticus, who was immediately enthusiastic about the new ideas, that he was persuaded to write his views in a book. Rheticus would take care of the printing of the book.

So Copernicus wrote his famous book "De Revolutionibus Orbium Coelestium" around 1540. The handwritten draft is still preserved today. The printing of the book took a long time. For one thing, it was a difficult text that Copernicus had changed over and over again in many places. Then we had to make woodcuts of the complicated graphics for the book, a total of 142 pieces! On the other hand, book printing was relatively new and not yet automated, and many works were still waiting to be printed. At that time the printing works were busy printing Martin Luther's writings.

Shortly before the book was finished, Rheticus was appointed to the University of Leipzig, which is why he had to transfer his work on Copernicus' book to someone else. Copernicus himself was seriously ill at that time, he had suffered a stroke. And so it came about that an Andreas Osiander supervised the printing.

Andreas Osiander knew the contents of the book and was afraidthat it would be banned by the Church as soon as it appeared. Therefore, without anyone knowing about it, he wrote an introduction in which it says that one should not regard the theses of Copernicus as real, but rather as a mathematical model that can be used to calculate the stars. Osiander did not sign the preface with his name, so that later many believed that Copernicus himself wrote it. But those who knew Copernicus knew that he was serious about his new model of the planets.

The foreword was a scandalbecause it presented the great, new, revolutionary work of Copernicus as unreal, as a mere mathematical product that does not endure in reality. At the same time, however, it saved the book from the index of the church, which could accept this world model as a mere calculation aid. The book did not appear on the forbidden books index until 1616, but only in Italy.

Nicolaus Copernicus himself did not notice any more of this. He died in 1543 after another stroke. His finished book was brought to him on the day of his death. It is not known whether he saw the preface. The Copernican system, which puts the sun in the center and rotates the planets together with the earth on circular orbits around them, was not yet really realistic, but it was a big step in the right direction. Copernicus inspired subsequent astronomers to refine and improve the system and, most importantly, to defend it against the traditional prevailing opinion.


Nicolaus Copernicus had no intention of starting a revolution. He was a modest, reserved, almost withdrawn person. He worked for many years to improve the old existing system without releasing any of it. He only discussed it with friends. He didn't want to completely abolish the geocentric view of the world, just find better solutions for how the planets move.

He even allowed the crystal spheres to which the planets were supposedly attached to remain.Free floating celestial bodies were simply unimaginable at that time. He also did not change anything in the orbits on which the planets supposedly run. It was only Johannes Kepler found out around 70 years after Copernicus that the planets move on elliptical orbits.

The time is ripe for something new

For around 1400 years, almost no one had questioned the geocentric view of the world. Despite some inconsistencies, it explained the celestial mechanics observed quite well. But something was still wrong. The time was ripe for change, also in the sky. Copernicus alone would not have been able to achieve such a feat of unhinging the world and rearranging the heavenly bodies. He continued the work of many diligent thought leaders and diligent observers and was inspired by the ideas of others.

Perhaps he had got his hands on the work of Aristarchus of Samos, who, 1,800 years earlier, had expressed the view that the sun was in the center and that the earth would orbit it. He benefited from the translations of ancient Greek works by the Arabs, who not only transferred the content 1: 1, but also corrected or commented on obvious errors and carried out their own calculations.

In Europe, too, new translations of the ancient writings emerged, for example by Georg von Peuerbach and his pupil Regiomontanus, who translated Ptolemy's Almagest into Latin, discovered errors, added numerous comments and wrote a more understandable summary.

Society was also changing in Copernicus' time. Book printing was invented by Johannes Gutenberg only about 100 years earlier, which led to the rapid spread of books and thus knowledge. Until then, books were a privilege of the rich and the clergy. Monks copied books by copying them, which took a correspondingly long time. Books were not generally accessible, but were kept in monastery libraries.

With book printing one was now able to make many inexpensive copies of a book in a short time. This led to the rapid spread of books even among the less privileged population. Copernicus was able to fall back on the knowledge of antiquity in book form, and his own work could also be brought to the people in this way.

Besides, the Reformation was just beginning. Martin Luther nailed his famous theses to the church door in Wittenberg in 1517 and thus triggered a split in the church. Religious unrest, persecution and peasant uprisings were the result, the existing system was called into question and experienced violent shocks.

There was also a revival of seafaring, which urgently needed precise astronomical dataIn order not to get lost on the world's oceans, because the seafarers could only orient themselves on the water, apart from the compass, by the course of the stars. In 1492 Columbus even discovered a completely new, gigantic continent that had not yet been entered on any map of the world. All he wanted was to go to India and save himself the detour around the whole of Africa by going around the world and reaching India from the other side.

Since the new double continent became known and explored, the old world globes and world maps were worthless. Ptolemy himself had made maps of the world because he was also a great geographer. But now, during Copernicus' lifetime, it turned out that the cards were wrong. Shouldn't one then also doubt Ptolemy's cosmology?

Society was changing, traditional ideas were now being challenged or thrown overboard. The known world had grown larger and new ships set out to make new discoveries. Everything was affected by changes. Indeed, the time was ripe for a new worldview. The ideas of Copernicus were not really new, but could not prevail until then. For the Copernican system, too, it took another 100 years before it was generally accepted.

Proof of its correctness could not initially be provided. This was only achieved by Galileo Galilei after the invention of the telescope. Johannes Kepler finally helped the heliocentric worldview to its right when he discovered the laws according to which the planets rotate around the sun.

Tags: astronomer, history of astronomy

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