Copernicus was afraid. The well-known astronomer and mathematician had worked his whole life on a new theory; but when it came time to tell it to the world, he hesitated. He feared that other astronomers and church leaders would think him foolish or, even worse, crazy. His idea—that the sun was the center of the universe, not Earth—contradicted the teachings of ancient Greek astronomers and the church. His theory moved not only Earth, but humankind as well, from the center of the universe. It was a revolutionary idea: how could humanity not be the most important part of the universe?
Nicolaus Copernicus was born to a wealthy merchant family in Toruń, Poland, on February 19, 1473. He was only ten when his father died, and his uncle, a bishop in the church, provided for young Nicolaus’ education, steering him toward religious studies. Nicolaus studied religion and medicine in Poland and Italy. His religious work included the study of astronomy, because the church used the positions of the planets to determine the dates of church holidays. And astronomy, along with astrology—how the movement of planets and constellations affects life—was also part of his medical studies. Doctors consulted the positions of the planets to determine why a person might be sick or whether treatment might be effective on a particular day. Of all the subjects he studied, Copernicus loved astronomy most; he said this science offered "unimaginable mental bliss."
But Copernicus’ uncle arranged for his nephew to work in the church, not as a scientist. After Copernicus finished his studies in 1503, he worked for his uncle as a secretary and physician. When his uncle died in 1512, Copernicus began to work as a canon, an administrator for the church, in Frombork, Poland. Canons collected rents and contributions to the church, managed land deals, and did all that was required to govern a small territory. Copernicus performed all these duties and once was even called to be a negotiator and military leader—beating back an invasion of Olsztyn Castle. In addition to his duties as canon, he was physician to bishops, other canons, and villagers. This made him a very, very busy man. Unlike university professors who devoted all their energies to their science, Copernicus was able to pursue astronomy only part-time. He was still able to make many observations, however, and read books by astronomers and mathematicians. Astronomy was always on his mind; he even sketched his ideas on the walls of his rooms.
Copernicus’ goal was to develop simpler formulas to accurately predict where the heavenly bodies would be on any given day. Up to that time, most people relied on the Greek astronomer Ptolemy’s book, written over 1300 years earlier, to predict the positions of the planets from day to day. In Ptolemy’s model, Earth was at the center of the universe, with the sun, moon, planets, and other stars circling it. However, his model did not calculate the length of the year exactly. As a result, the calendar had shifted over time, and the actual positions of the heavenly bodies no longer matched where they should be according to the calendar. This meant that the calendar could not predict when church holidays should take place. For instance, Easter must be celebrated on the first Sunday after the first full moon following the spring equinox, the day the sun is directly above Earth’s equator. But because Ptolemy’s calculations were inaccurate, Easter was no longer being celebrated on the right day of the year.
Copernicus found that he could predict the heavenly bodies’ positions simply and accurately if he assumed the sun, and not Earth, was at the center of the universe, with the planets orbiting around it. Earth was demoted from the center of the universe to just another planet, the moon being the only heavenly body that orbited around it. He was convinced the planets revolved around the sun, writing, "Who would place this lamp of a very beautiful temple in another or better place than this, wherefrom it can illuminate everything at the same time?" He realized that Earth spins on an axis, causing night and day. He determined the distances from the sun to each planet and the order of the then-known planets from the sun: Mercury, Venus, Earth, Mars, Jupiter, and Saturn. This order explained why the planets seem to sometimes move backward when viewed against the stars, a phenomenon Ptolemy couldn’t easily account for. Copernicus also theorized that the reason the stars appear "fixed" is that a huge distance separates them from Earth, which suggested that our planet is tiny relative to the whole universe. In 1514, Copernicus circulated his ideas among a few friends and fellow astronomers in a six-page, handwritten book called Little Commentary. He promised a future book with the calculations to prove his theory.
Copernicus was not the first to think the sun was the center of the universe, but he was the first to write a book that proved such a system possible. Since he was working on the book in his spare time, it took more than thirty years for him to develop the formulas for his theory. He was still working on his computations in 1539, when a young astronomy professor named Georg Joachim Rheticus became his assistant. Rheticus convinced Copernicus to publish his work and helped him put the final touches on the manuscript. Rheticus took it to be published in September of 1541; however, he accepted a position at a university far from the publisher and passed on supervision of the publishing process to a priest named Andreas Osiander. Osiander felt that Copernicus’ theory went against the teachings of the church, so he added a preface explaining that this system was not a new view of the world, but merely an easier way to calculate the positions of the planets. Since Osiander didn’t sign the note, people assumed it had been written by Copernicus. The book, On the Revolutions of the Heavenly Spheres, was published in 1543, and it is said Copernicus finally received a copy of it on his deathbed on May 24 of that year.
Because of Osiander’s note, the book was not considered at all revolutionary when it was first published. It was not until Galileo Galilei used Copernicus’ theory, more than sixty years later, that the book was understood for what it was: a new and more accurate view of the universe. The book was then banned by the church, confirming Copernicus’ fear from so many years earlier.
Copernicus’ model was not totally correct—we now know the universe is not centered around our sun, but made up of billions of galaxies, each consisting of billions of stars. But Copernicus had the courage to state his revolutionary observations and the skill to provide mathematical proof for his theory. His work demonstrated that planets and stars do not circle around Earth; our planet is merely a tiny part of a much larger system of heavenly bodies. By providing the key to our universe, his work became a crucial stepping-stone for generations of scientists to come.