Nicolaus Copernicus

Nicolaus Copernicus was a Polish astronomer known as the father of modern astronomy. He was the first modern European scientist to propose that Earth and other planets revolve around the sun, or the Heliocentric Theory of the universe. 

Prior to the publication of his major astronomical work, “Six Books Concerning the Revolutions of the Heavenly Orbs,” in 1543, European astronomers argued that Earth lay at the center of the universe, the view also held by most ancient philosophers and biblical writers. 

In addition to correctly postulating the order of the known planets, including Earth, from the sun, and estimating their orbital periods relatively accurately, Copernicus argued that Earth turned daily on its axis and that gradual shifts of this axis accounted for the changing seasons. 

Nicolaus Copernicus was born on February 19, 1473 in Torun, a city in north-central Poland on the Vistula River. Copernicus was born into a family of well-to-do merchants, and after his father’s death, his uncle–soon to be a bishop–took the boy under his wing. He was given the best education of the day and bred for a career in canon (church) law. At the University of Krakow, he studied liberal arts, including astronomy and astrology, and then, like many Poles of his social class, was sent to Italy to study medicine and law. 

The cosmology of early 16th-century Europe held that Earth sat stationary and motionless at the center of several rotating, concentric spheres that bore the celestial bodies: the sun, the moon, the known planets, and the stars. From ancient times, philosophers adhered to the belief that the heavens were arranged in circles (which by definition are perfectly round), causing confusion among astronomers who recorded the often eccentric motion of the planets, which sometimes appeared to halt in their orbit of Earth and move retrograde across the sky. 

In the second century A.D., the Alexandrian geographer and astronomer Ptolemy sought to resolve this problem by arguing that the sun, planets, and moon move in small circles around much larger circles that revolve around Earth. These small circles he called epicycles, and by incorporating numerous epicycles rotating at varying speeds he made his celestial system correspond with most astronomical observations on record. 

The Ptolemaic system remained Europe’s accepted cosmology for more than 1,000 years, but by Copernicus’ day accumulated astronomical evidence had thrown some of his theories into confusion. Astronomers disagreed on the order of the planets from Earth, and it was this problem that Copernicus addressed at the beginning of the 16th century. 

Sometime between 1508 and 1514, Nicolaus Copernicus wrote a short astronomical treatise commonly called the Commentariolus, or “Little Commentary,” which laid the basis for his heliocentric (sun-centered) system. The work was not published in his lifetime. In the treatise, he correctly postulated the order of the known planets, including Earth, from the sun, and estimated their orbital periods relatively accurately. 

In “Six Books Concerning the Revolutions of the Heavenly Orbs,” Copernicus’ groundbreaking argument that Earth and the planets revolve around the sun led him to make a number of other major astronomical discoveries. While revolving around the sun, Earth, he argued, spins on its axis daily. Earth takes one year to orbit the sun and during this time wobbles gradually on its axis, which accounts for the precession of the equinoxes. 

Nicolaus Copernicus died on May 24, 1543 in what is now Frombork, Poland. He died the year his major work was published, saving him from the outrage of some religious leaders who later condemned his heliocentric view of the universe as heresy. 

It was not until the early 17th century that Galileo and Johannes Kepler developed and popularized the Copernican theory, which for Galileo resulted in a trial and conviction for heresy. Following Isaac Newton’s work in celestial mechanics in the late 17th century, acceptance of the Copernican theory spread rapidly in non-Catholic countries, and by the late 18th century the Copernican view of the solar system, it was almost universally accepted.