Copernicus, Nicolaus
1473–1543
Polish astronomer

In the early 1500s, astronomer Nicolaus Copernicus challenged the ancient Greek model of the universe. This long-accepted view stated that Earth was at the center of the universe and the Sun and planets revolved around it. Copernicus developed a new system with the Sun at the center of the universe. Though not widely accepted during his time, Copernicus's new vision of the universe laid the foundations of modern astronomy.

Life and Scholarship. Born in Torun, Poland, Copernicus lost both his parents by age 12. His uncle, a priest who later became a bishop, cared for the boy and gave him an education. Copernicus attended a church school and later studied at the University of Cracow. Through his uncle's influence, Copernicus gained a lifetime position at the cathedral of Frauenberg (present-day Frombork) in Poland. The administrators of the cathedral sent him to Italy to study church law. Copernicus also studied astronomy in Italy. His first recorded observation, in March 1497, was of the Moon passing in front of the star Aldebaran.

Between 1499 and 1501 Copernicus gave a few lectures on astronomy and mathematics in Rome, observing a lunar eclipse while he was there. He received his degree in church law in 1503 and also became a licensed physician. He then returned to Frauenberg, where he spent the rest of his life serving in his church and making important astronomical discoveries.

Though he is best known for his work in astronomy, Copernicus also contributed to several other fields of scholarship. In his position as a church administrator, he produced several works on money and the economy. He also standardized the weights and measures in his region. In 1509, he published a translation of a Greek literary work. Copernicus's knowledge of Greek enabled him to read a work by the ancient Greek astronomer Ptolemy, which was not then available in Latin.

Astronomical Works. In 1513 Copernicus built a roofless tower for observing the sky and tracking the positions of the Sun, Moon, and stars. A year later he had written the first draft of Little Commentary, his first description of a theory that would revolutionize astronomy.

For nearly 2,000 years, scholars had based their view of the universe on the works of Ptolemy. According to Ptolemy, Earth stood in the center of the universe, and the Sun, Moon, and planets revolved around it in large circles. Ptolemy's model of the universe showed the Moon circling nearest Earth, followed by Mercury, Venus, the Sun, Mars, Jupiter, and Saturn.

Copernicus proposed a new model in which the Sun held the central position and the planets revolved around it. Earth occupied the fourth position from the center, where the Sun had been in Ptolemy's model. Copernicus stated outright that objects in the heavens do not revolve around Earth. They only appear to do so because Earth itself is moving, spinning once on its axis every day and revolving once around the Sun every year.

Copernicus was concerned about the consequences of creating a new model of the universe. One reason was that the Roman Catholic Church, of which he was a loyal member, strongly supported the Greek model. He pondered his findings for 26 years before making them available to the public. Finally, at the urging of several friends and colleagues, Copernicus allowed the young scholar Georg Rheticus to write a summary of his manuscripts. In 1540 Rheticus published his "First Report" of Copernicus's new system.

A full mathematical explanation of Copernicus's sun-centered system appeared in 1543. The six-part work, titled On the Revolutions of the Heavenly Spheres, did not raise controversy at first. Its editor added a preface by a theologian* who described the system as merely a tool for calculating the positions of heavenly bodies, rather than a factual view of the universe. Over time, however, the sun-centered view began to attract support from astronomers such as Galileo Galilei. In 1616 the Catholic Church placed On the Revolutions of the Heavenly Spheres on its list of forbidden books, where it remained until 1758.

Most scholars agree that Copernicus greatly simplified the study of the solar system. In order for Ptolemy's theory to fit their observations, astronomers had burdened the system with 55 special calculations and adjustments. Copernicus's system, while not perfect, reduced that number to 34. It also laid the groundwork for later scientists, such as Galileo and Johannes Kepler, to develop more useful theories of the universe.

(See alsoAstronomy; Index of Prohibited Books; Science. )

* theologian

person who studies religion and the nature of God