A young astronomer rediscovered a revolutionary truth about the universe. Then he delayed publishing his story for decades._ Excerpt from “Dava Sobel: A More Perfect Heaven,” November 7, 2011.

DAVA SOBEL, Author, Longitude, Galileo’s Daughter, and A More Perfect Heaven:
How Copernicus Revolutionized the Cosmos; Science Writer

I got the idea of writing this book in 1973, because that was the 500th anniversary of [Nicolaus Copernicus’] birth. I remember reading an article about him in Sky & Telescope that talked about how he finally got convinced to publish his insane idea. A stranger came to talk to him about his ideas, pushed him to do what he’d avoided doing his whole life.

He got the notion of a suncentered plan for the cosmos – which at that time was a most unpopular idea – as a young man. He wrote about it to a few people he knew would be interested. This was how scientists disseminated their ideas in an age before scientific journals. They wrote letters, and then the scientists who received those letters could copy them over and send them to other people, and the ideas spread around slowly. That kind of activity is what made Copernicus’s reputation known, even though he had no kind of university affiliation – no community of scholars – near him anywhere in Poland that he could talk to about these ideas. Everything was by Latin correspondence.

He outlined his plan, that it would make a lot more sense for the earth to be in motion around the sun, even though it doesn’t seem to be moving, and that he was at work on a book that would explain the whole idea and give the background math, and that would come eventually. People began to know he was at work on this project.

Some people think it took Columbus – who made his voyages while Copernicus was a college student – to convince everybody that the earth was round. This is a fiction created by Washington Irving in the 19th century. People have always known that the earth was round. It is really obvious. Because if you travel very far from north to south, you see different stars coming up; you’d see ships sailing away, they disappear from the bottom up, and when they come home, they appear from the top down.

Every now and then, a lunar eclipse happens; you actually see the shadow of the round earth falling on the surface of the moon. People have been observing eclipses and recording them and predicting them since the 8th century B.C. From our vantage point on the planet, it really looks as though everything is moving around us. We don’t have any sense that we’re moving. If you throw something in the air, it doesn’t land 100 feet behind you. So how could we be moving? These kinds of commonsense notions of stability really made Copernicus worry about publishing his idea widely.

Copernicus had a predecessor on the notion of a sun-centered system, and that was Aristarchus in the 3rd century B.C. He wrote a book about this idea that the earth was in motion around the sun, and he understood that that meant the stars would have to be much farther away than people thought, because for the earth to go all the way around the sun every year, you would see some change in the stars – they would look bigger or smaller or closer together – and we don’t see that. Aristarchus understood all of those things; the problem was that his book disappeared in antiquity. Another book he wrote, on the sizes and distances of the sun and the moon, survived, and Copernicus read that book. But the only trace of Aristarchus’ sun-centered system was in a book by Archimedes, called The Sand Reckoner, in which he refers to Aristarchus’ idea and explains it in a long paragraph. But that book did not come into Europe, get translated into Latin, and get published until a year after Copernicus died.

Ptolemy was the reigning authority on astronomy. He had written a book in the 2nd century that was still considered the authoritative word on astronomy in Copernicus’ time, the late 15th through the middle of the 16th century. Even Ptolemy had said that in some way, it would make sense for the earth to move than to try to think of all the stars and planets all going around this one tiny little sphere, except the motion of the earth was too ridiculous even to consider.

Ptolemy’s book made mathematical explanations for the motions of the planets. It violated an ancient belief about the heavenly motions, that they should proceed in uniform speed in perfect circles. Of course, they don’t really move that way. So if you’re looking from the earth and trying to create a system that accounts for all their motions, you’ve got to bend the rules somewhere, and Ptolemy did that. He figured the motions from a point that wasn’t really the center. This really bothered the Arabic astronomers of the 13th century, and they worked to revise Ptolemy’s math. Copernicus definitely saw this work. He was a student at a time when manuscripts were coming to Europe from all over the world, and he was aware of this work and actually lifted it for his own calculations. However, the Islamicastronomers never switched places between the earth and the sun; they didn’t see any need to do that.

That was what Copernicus did. Somehow he saw the footprint of the earth’s motion in the patterns of the other planets, and he just tried it to see what would happen. When he put the sun at the center, the planets lined up in order of their speed, which must have struck him as something totally wonderful, because it gave a reason for the planets to have different speeds: It had something to do with their distance from the sun. Before that switch, people didn’t know the order of the planets; if earth was at the center, then the moon is the first thing to go around, and after that, you were hard-pressed to say whether [the next planet] is Mercury, Venus, or the sun. When you get beyond that, the rest of the order works out, but it’s foggy in the middle. With the sun in the center, it made complete sense. He had a fully developed system that must have struck him as reality. In his time, people didn’t think you could discover anything real or true about the heavens. For him to think he understood the actual structure of the universe was a gigantic claim.

The path to going public
Copernicus’s great book, On the Revolutions of the Heavenly Spheres, had been dismissed by Arthur Koestler in The Sleepwalkers as the book nobody read. Owen Gingerich thought that probably wasn’t true, and he has made a lifetime career of tracking down all the extant copies of Copernicus’s book. He has been able to prove that everybody read his book.
Copernicus made the sun stand still in his theory, but that was the text from the Book of Joshua that he most worried about, because he knew people who didn’t understand astronomy would use the Bible against him, would twist chapter and verse to discredit him. One of the questions he most expected to be asked was, “If the sun is standing still at the center, as you claim, why did Joshua have to tell it to stand still?”

I wanted to go to Poland and see all the places Copernicus had lived, because he left a very thin historical record. There’s his book; there are some other pieces that he published about astronomy; but there are only 17 letters. Galileo left 1,000 letters, so 17 letters is not much, and I was looking for anything else that would help me get to know him better.

He lived up on the northern coast. [In] 2005, I was on a trip to see an eclipse in the middle of the Pacific Ocean. One night at dinner, I sat next to a young Polish mining engineer. I told him I was going to be making a trip to his country; I was working on a project about Copernicus. I’ve always maintained that amateur astronomers are the most generous people. They just love to take the telescope out somewhere, and have people who’ve never looked through one come by and get a thrill. So I’m chatting with this young man about my trip, and it didn’t take him five minutes to say, “You must give me the dates of your travel. I will get the time off work, and I will be your translator and guide.” I had no idea how much I would need a translator and guide, so it was really a good thing that he offered to do that for me. He actually did it twice, and refused any kind of payment – just a wonderful companion. His name is Thomasz Mazur, and we saw many wonderful things together: all the castles where the knights lived, the birthplace museum of Torun, where Copernicus was born.

[Copernicus made] a few scientific instruments that helped him establish the positions of the planets against the background stars or in relationship to the moon. It has sighting veins, and you look through those at an object, and as you’re sliding this arm along the other one, when you get the object lined up, then you have a reading – an angular measurement above the horizon.

Another thing he was doing was dealing with the peasants. The Church owned all the land and would rent it out to the peasants so they could raise their crops and animals. The peasants nominally owned their parcels of land, so they could deed them to their children or they could sell them to a neighbor. Copernicus had to travel all around these thousands of acres and record every such transaction and collect the rent. That was something I found very useful to help establish his character, because you can see in the way he settled disputes among the peasants that he was extremely fair to them.

[In the building] where he lived, on the wall that was open to the light, he fashioned [a] sundial. With this instrument he was able to figure out the exact length of the year. This was another big problem. There were problems with the calendar; the length of the year had been miscalculated, so Easter was falling out of sync with the seasons, and the popes were eager for calendar reform and were periodically asking all the astronomers to contribute their ideas on how to fix the calendar. So he was working on that.

He was also interested in economics, because, in the process of collecting all this money from the peasants and seeing the kind of currency that was circulating, he realized all the abuses of the coinage. There were minting privileges in many cities, and local governors could just issue new coins whenever they felt like it with a lower content of silver. You can imagine what happens. The coins have the same face value as the others, but they weigh less and have less silver, so smart people hoard the coins with the more silver in them, because they can always take them to the goldsmith and get them melted down. They spend the less valuable ones. Copernicus wrote a treatise on that and other problems with the coinage. The Polish senate ... actually listened to him and implemented his changes.

Right around the time Copernicus was writing this treatise about money, Martin Luther published his complaints about Church practices. Things really began to change in Europe. Copernicus, being Catholic [and] working for the Catholic Church, soon felt the pressure of the new evangelist religion, and neighboring bishops sometimes converted to Lutheranism, so Copernicus’s diocese became more and more isolated. Meanwhile, Copernicus’ idea got more and more widely known. [A] map was published in the early 1530s, a good 10 years before his book finally came out. [On the map], up at the North Pole, and down at the South Pole, there are little crank handles on the earth [with] little cherubs actually turning the cranks. So the idea is abroad that maybe the earth is not quite as stationary as people have thought.

In 1539, Copernicus suddenly received a visit from a young German mathematician. Rheticus was 25 years old. He showed up at Copernicus’s door having heard about this idea. He was an outcast, because the bishop had grown so paranoid that he had issued an edict banishing Lutherans from the diocese. The last thing Copernicus needed was a heretic in his house. He was already in trouble with the bishop because of his female housekeeper. Three of the 17 letters are about the bishop’s anger and outrage over the presence of this unmarried woman in his house, so Copernicus was forced to send her away. He no sooner gets rid of her than the Lutheran arrives to encourage him to publish the book he has avoided publishing all this time.

By some finagling, they managed to keep Rheticus in residence for two years. He obviously convinces Copernicus; he brings him observations of the planet Mercury that Copernicus had not been able to make himself – so that was another encouragement – and he wrote his own summary of Copernicus’s theory and had it published just to see what would happen. Now what would the reaction be? It is written as a letter to the man who told Rheticus about Copernicus’s ideas. They got this published in 1541, and nothing happened. The world didn’t explode. That was another inducement to Copernicus to publish the full-blown treatise.

They had a lot of work to do on the manuscript. One thing Rheticus had to do was copy the entire manuscript. It’s a great big book, 400 pages printed, but Copernicus obviously did not want to part with his original; he had had it his entire life, and he insisted on keeping it. This manuscript still survives, which is so unlikely, because at that time, in the printing process, the manuscript got distributed among the various typesetters, and each one worked on his part and then threw the pages away. The manuscript no longer existed once there was a printed book. But Copernicus insisted on keeping his.

The book, today – if you find one at auction – costs upwards of $2 million. So what price do we put on the original manuscript? That’s why they keep it in a safe, and of course for its own protection from insects, floods. We were able to request several openings of the manuscript. It’s bound, and a curator brought it in and opened the book to [a] page [showing a diagram]. The real manuscript not only shows the diagram, but he continues writing around the diagram. It’s beautifully done in his tiny, neat handwriting.

When we saw this page, we both gasped, because there’s a hole in the middle of the page. If you draw concentric circles with a pair of compasses, you get a hole in the middle of the page, and that, really, was the moment I felt I had seen him brush through the room. Then it was over, and we had to leave. Walking out of the building, Tom said, “It was just like an eclipse. It was over too soon, but you’ll never forget it.”