Copernicus, the Universe and the Church

Astronomer Nicolaus Copernicus was born in Torun, Poland in 1473. He laid the foundation for modern astronomy by disputing the widely held belief that the Earth was the center of the universe. Instead, he pronounced that Earth, and the other planets, revolved around the Sun. This theory caused profound shock and a revolution in scientific and philosophical thought.

The Christian Church, Protestants, and Catholics alike believed that God had created the Universe just for mankind and so the Earth must be the center of it. That did not fit with what Copernicus knew about physics and the motion of the planets. With that belief, he couldn't make the math work or match his observations. He realized that if he created a new model and moved the Sun to the center, the equations all functioned much more smoothly.

Sometime between 1510 and 1514, Copernicus published his "Little Commentary" on his new model, a 40-page outline of his heliocentric — sun-centered — universe, which he sent to various astronomers while he continued working on a much longer, more detailed discussion of the idea. 

The expanded work was On the Revolutions (1543), which Copernicus dedicated to Pope Paul III, hoping the Pope would protect him from vilification for having removed the Earth from its sacred place. On the Revolutions hardly created a revolution when he wrote it; it was groundbreaking and controversial but, contrary to popular lore, the Church didn't immediately condemn him for it.

There were also those before Copernicus who had posited similar theories. Philolaus (c. 470 – c. 385 BCE) described an astronomical system in which a Central Fire (different from the Sun) occupied the center of the universe, and a counter-Earth, the Earth, Moon, the Sun itself, planets, and stars all revolved around it, in that order outward from the center.

Heraclides Ponticus (387–312 BCE) proposed that the Earth rotates on its axis. 

Aristarchus of Samos (c. 310 BCE – c. 230 BCE) was the first to advance a theory that the Earth orbited the Sun. Further mathematical details of Aristarchus's heliocentric system were worked out around 150 BCE by the Hellenistic astronomer Seleucus of Seleucia. Though Aristarchus's original text has been lost, a reference in Archimedes' book The Sand Reckoner (Archimedis Syracusani Arenarius & Dimensio Circuli) describes a work by Aristarchus in which he advanced the heliocentric model.