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For Copernicus, A 'Perfect Heaven' Put Sun At Center
It doesn't happen often, but there are times when a single book turns the world on its head. Isaac Newton's Principia unraveled the mystery of gravity. Charles Darwin's On the Origin of Species explained how evolution worked.
But before either of these, there was On the Revolutions of the Heavenly Spheres by Nicolaus Copernicus. It was published in 1543. In it, Copernicus made the astounding claim that Earth revolves around the sun, not the other way around.
In the year 1500, every learned person in Europe knew one thing for absolutely certain: The sun and the planets travel around Earth. All astronomy texts said so. The Bible said so. There was no doubt.
Oh, sure, there were a few bits of conflicting evidence. For example, the planets seem to move first one way and then the other in the sky. But never mind that. Earth was at the center of the universe. Period.
And then came Copernicus.
"He put the Earth, which had forever been considered the immobile center of the universe, he spun it on an axis and had it moving around the sun," says Dava Sobel, author of A More Perfect Heaven: How Copernicus Revolutionized the Cosmos. Although the idea that the sun, not Earth, was at the center of things was outrageous, it did solve the problem of the planets appearing to move backward.
"If you have the Earth in motion, then you can show that that strange backward drift of some of the planets is a result of the Earth moving faster and overtaking them on an inside track so that they look like they're stopping and moving backward," she says.
Today, every kid in school learns that Earth goes around the sun. In 1510, it was a hard concept to grasp.
"It went against everything that your senses tell you. It went against common sense, it went against your feeling that certainly the ground underneath you is not moving, is not spinning around," says Sobel.
Violating common sense wasn't the only problem in the 16th century with a theory that called for Earth to move. "There was a biblical prejudice against the Earth's motion. And Copernicus really worried about that," says Sobel.
It might have been that worry that caused Copernicus to delay publication for three decades. It might have been fear of ridicule for his crazy ideas. But apart from some correspondence with other astronomers, Copernicus kept his theories to himself.
That changed when he received a visit from Rheticus, a young German mathematician. Rheticus had heard of Copernicus' theories and was inspired to make the arduous and risky journey to Poland to meet the aging astronomer. Sobel's book contains a play imagining how Rheticus convinced Copernicus to share his theories with the world.
On the Revolutions of the Heavenly Spheres was finally published in 1543, and nobody seemed too upset. "Copernicus' ideas were already being taught in the universities in the 16th century," says Robert Westman, a historian of science at the University of California, San Diego, and a visiting fellow at the Huntington Library. "But they were taught and immediately dismissed as absurd."
Westman, author of The Copernican Question: Prognostication, Skepticism, and Celestial Order, says it took awhile for scholars to accept Copernicus' ideas. "I venture to say there's nobody around who accepts Copernicus' theory today because they've read his book. It's a very unfriendly book. And even in the 16th century, it was seen to be difficult to read."
Galileo, not Copernicus, took the heat for insisting Earth was in motion, not fixed at the center of the solar system.
Westman says any sophisticated scientific argument that seems to defy common sense will be hard for nonscientists to accept. Take the strange weather patterns we're beginning to see around the world. How does a nonscientist decide if that's related at all to climate change?
"It depends on which authorities you trust," says Westman. "If you trust the scientific community, then you might be willing to say it has something to do with global warming. But it's not because you go to your laboratory and do experiments."
While the public debate over global warming continues, the debate over Copernicus' theories is long over. In fact, his book is regarded as a global treasure. If you want to buy a first edition for your home library, it will cost you about $2 million.