Nicolaus Copernicus Or, how we suddenly realized we aren’t as important as previously thought. And science.

Geocentric Conceptions Greek astronomers believed in a geocentric model in which the Earth was the center of all celestial bodies. This was supported through observation.

Why believe a geocentric model? Two observations backed up this model – The sun, stars and other celestial bodies appeared to move around the Earth each day. Everything circles back to the same point each day. – The Earth did not appear to move from the perspective of someone on it – therefore Earth is solid, stable and unmoving.

Ptolemaic System Greek Astronomer Ptolemy introduced ideas similar to geocentrism but accounting for changes in season length. Each celestial body moves in two spheres: deferent and epicycle. Earth is slightly off center

Who was Nicolaus Copernicus? Not much is known about his childhood and early schooling. Assumption that he was well educated – spoke Polish, Latin, German, Greek and Italian. A polyglot! Born in Poland in 1473 at the height of the Renaissance

Copernicus was a badass polymath A person whose ‘expertise spans a significant number of different subject areas’ and who ‘draws upon complex bodies of knowledge to solve problems’

What have you done today? Copernicus was a … – Lawyer (specializing in canon law) – A practicing physician – Economist (created Quantity Theory of Money) – Mathmetician (most accurate orbits to date) – Astronomer (duh) – Diplomat (with and, later, for his uncle)

Commentarioulus (Little Commentary) In 1514, Copernicus released his theory of a heliocentric system to close friends. Contained ‘assumptions’ on the universe. Involved little mathematical support at this point.

Publish dude! By 1532, Copernicus has finished his full manuscript of On the Revolutions of Heavenly Bodies but, despite urging from peers, would NOT PUBLISH his work. Did not wish to risk the doubt “to which he would expose himself on account of the novelty and incomprehensibility of his thesis.”

Copernican Assumptions 1. There is no one center of all the celestial circles or spheres. 2. The center of the earth is not the center of the universe, but only of gravity and of the lunar sphere. 3. All the spheres revolve about the sun as their midpoint, and therefore the sun is the center of the universe. 4. The ratio of the earth's distance from the sun to the height of the firmament (outermost celestial sphere containing the stars) is so much smaller than the ratio of the earth's radius to its distance from the sun that the distance from the earth to the sun is imperceptible in comparison with the height of the firmament.

Copernican Assumptions 5. Whatever motion appears in the firmament arises not from any motion of the firmament, but from the earth's motion. The earth together with its circumjacent elements performs a complete rotation on its fixed poles in a daily motion, while the firmament and highest heaven abide unchanged. 6. What appear to us as motions of the sun arise not from its motion but from the motion of the earth and our sphere, with which we revolve about the sun like any other planet. The earth has, then, more than one motion. 7. The apparent retrograde and direct motion of the planets arises not from their motion but from the earth's. The motion of the earth alone, therefore, suffices to explain so many apparent inequalities in the heavens.

On the Revolutions of the Heavenly Bodies (1453) Copernicus’s famous text was dedicated to Pope Paul III, whom Copernicus asked to protect him from vilification. In this letter, Copernicus explains his reason for delaying the publication of his book.