Nicolaus Copernicus and the Heliocentric Universe

Imagine you discovered something important that nobody would believe. Even worse, your discovery might get you into trouble. That’s what happened in 1514.

Nicolaus Copernicus was a deeply religious man. He worked for the church and often cared for the poor in Poland, but at night, he studied the heavens. Copernicus measured the positions of the sun, moon, and planets and concluded that the sun is at the center, not the Earth. Helios is the ancient Greek word for the sun.

In Copernicus’ time, almost everyone believed that the Earth was the center of the universe. People believed that the sun and other heavenly bodies moved in circles around the Earth.

Fear and Faith

Copernicus feared that his ideas did not agree with how some people interpreted the Bible, so he was careful to share them with a small group of scholars. Martin Luther, a leading religious figure of the day, criticized the idea, saying, “Scripture tells us that Joshua commanded the sun to stand still, and not the earth.”

A legend about Copernicus tells of a book he wrote about the sun-centered universe. The book was placed in his hands a few days after he lost consciousness from a stroke. The story has it that Copernicus awoke to see that his work had been published, and then died peacefully. We don’t know if that story is true, but it shows how difficult it could be to challenge long-held beliefs, even when new ideas question what people had always accepted.

Aristarchus of Samos

Nearly two thousand years before Nicolaus Copernicus, a Greek astronomer named Aristarchus of Samos used geometry to study the moon’s phases and estimate the sun’s distance. From this, he concluded that the sun was much larger than Earth and proposed that Earth moved around the sun. Aristarchus’s heliocentric theory was known to later writers such as Archimedes and Plutarch, but the idea that Earth traveled around the sun did not gain widespread acceptance in the ancient world. Most scholars followed Aristotle and Ptolemy, who taught that Earth stood still at the center. Others rejected Aristarchus’s idea because they could not see the stars shift in the sky as Earth moved. There is no clear evidence that Nicolaus Copernicus knew of Aristarchus, so he may have developed his theory independently.