Nicolaus Copernicus was a priest in Poland who developed interest in Astronomy. In 1508, at the age of 35, he had begun developing his own celestial model, a heliocentric planetary system. Ptolemy had previously invented a geometric planetary model, which was inconsistent with Aristotle’s idea that celestial bodies moved in a circular motion at different speeds around a fixed point, the earth. In an attempt to reconcile such inconsistencies, Copernicus’s heliocentric solar system named the sun, rather than the earth, as the center of the solar system. Subsequently, Copernicus believed that the size of each planet’s orbit depended on its distance from the sun. He went on to design and apply a complex mathematical system for proving his theory. In 1513, his dedication prompted him to build his own modest observatory so that he could view the planets in action at any given time.
He documented his great work in De Revolutionibus orbium coelestium libri sex (Six books on the Revolutions of the Heavenly Spheres). De Revolutionibus is divided into six sections, or “books”. The first of these books sets out Copernicus’ heliocentric theory as the basis for his cosmology and ongoing calculations; the second book uses trigonometry to solve various motions of heavenly bodies in the sky; book three looks at the motion of the Earth; book four, the motion of the Moon; and books five and six, the motions of the planets. When it was published in 1543, just before Copernicus’s death, religious leader Martin Luther voiced his opposition to the heliocentric solar system model.
Interestingly, although apparently contradicting the Bible, the book avoided serious censorship until 1616, seventy three years after first publication, when it was placed on the Catholic Church’s Index of Prohibited Books. The ban was lifted at the end of 17th century. The book has been described as a “monument of scientific genius” and marks a huge and important stride forward in human understanding of the natural world.