What are Copernicus' contributions to the Renaissance?

Nicolaus Copernicus's greatest contribution to the Renaissance—and the world itself—is undoubtedly the heliocentric model of the solar system.

Before Copernicus published his theories on the universe, the generally accepted model of the universe was a geocentric model that assumed Earth was the center of the universe. Copernicus's model wasn't completely correct, but it was closer than that of others at the time. It also created a foundation for other scientists to build on.

Of course, Copernicus's views weren't widely accepted during his time. According to A&E's Biography: 

Around 1514, [Copernicus] shared his findings in the Commentariolus. His second book on the topic, De revolutionibus orbium coelestium, was banned by the Roman Catholic Church decades after his May 24, 1543 death in Frombork.

It took more than one hundred years after his death for people to take him seriously. His ideas were a serious challenge to the religious hierarchy of the time. Almost one hundred years later, Galileo Galilei was even punished for continuing Copernicus's ideas and saying that Earth revolves around the sun. The very idea was deemed heresy. 

One thing Copernicus achieved through the publication of his ideas was standing as a symbol of an educated scientist who was undermined by religious fundamentalists, according to the eNotes guide on Copernicus. Though other people later took that mantle, he still functioned as a rallying point for those who believed deeply in their ideas about science but were persecuted by religious figures. 

Copernicus did other things in his life. For example, he was the first person in Poland to translate Theophilactus Symocatta from Greek into Latin. He held many positions as well, from doctor to mapmaker to diplomat and advisor to the Prussian Diet. Still, though, his major remaining contribution to the Renaissance—and what he is well-known for—is his heliocentric model of the universe.

What key idea did Copernicus contribute to the Renaissance?

The key idea contributed by Copernicus is that the earth revolved around the sun rather than the other way around. This theory, known as "heliocentrism" was very radical. Copernicus's contemporaries, and most importantly the Catholic Church, accepted the ancient Ptolemaic theory, a "geocentric" model that placed the earth at the center of the universe. According to this model, the Earth was stationary. This view accorded with a literal understanding of the Bible, which, in several passages, seems to portray the Earth as a non-moving body. Copernicus's theory, published in the last year of his life in a book entitled De Revolutionibus, thus flew in the face of Church doctrine, and was banned by the Church. It should be noted that Copernicus's model needed significant revision, as it argued that the sun was at the center of the universe, with all the stars and other heavenly bodies revolving around it as well. Like Ptolemy, he thought orbits were traced along perfect spheres. Later astronomers, working from observation, showed that orbits were in fact elliptical, and that the sun was not the center of the universe.