Nicolaus Copernicus (1473-1543) published his heliocentric theory in 1543, just before his death. He realized that placing the Sun at the center of the universe with planets revolving around it made calculations and predictions much easier. This contradicted the geocentric Ptolemaic system that had been accepted for over 1400 years. Though his system was only slightly less complicated, it marked the beginning of replacing the Earth-centered view of the universe with one centered on the Sun. The Catholic Church initially ignored Copernicus' theory but eventually banned his book in 1616 as his ideas threatened established authority.

1. THE MODERN VIEW John Coltrane – Stairway to the Stars

2. A little review Geocentric Heliocentric Earth centered system- Sun centered system –

3. Mars shows both prograde and retrograde motion July 1 August 1 September 1 October 1 November 1

4. Ptolemaic System

5. Ptolemaic System

6. Ptolemaic system in trouble After 1400 years (late 16 th century) System began to seem clumsy Increasing levels of complexity to match observations Why? Better time keeping More and more epicycles needed

7. The historical context Columbus had explored the Americas (1492) Columbus thought the world was smaller It was the size Eristarchus had estimated

8. The historical context Europe was emerging from the Dark Ages into the Renaissance

9. The historical context Modern calendar adopted in 1582

10. The historical context By the 1500s… The Roman Catholic Church had been the biggest power in Europe for about 1200 years

11. The historical context Martin Luther led the Protestant Reformation (1517) Henry VIII of England places himself as head of Church in England (1534)

12. The historical context The Church’s power was under attack

13. Martin Luther

14. Astronomy and the Early Church Dates of holidays set by equinoxes and solstices The calendar was wrong Date of vernal equinox was slipping Easter was coming at the wrong time Needed more precise determinations of dates Easter?? At the wrong time ?? This will not do!

15. Questions: What is a system that orbits the Earth? Geocentric What is a system that orbits the Sun? Heliocentric In what direction do the planets usually move? East to west In what direction does a planet move when it is in retrograde motion? West to east

16. Questions: Why was the early church so interested in astronomy? Needed an accurate determination of holidays Dates were slipping

17. Nicolaus Copernicus (1473–1543) Wanted an easier system to use than Ptolemy’s Realized that a heliocentric system system made calculations/predictions much easier Published in 1543, just before his death

18. Copernicus

19. Copernicus’ Ideas (simplified) Earth is not at the center of everything All the planets revolve around the Sun The stars are much further away from Earth than the Sun

20. Copernicus’ Ideas (simplified) Any apparent motion we see is the result of Earth’s rotation The annual motion of the Sun (solstices, equinoxes) is actually because of Earth’s orbit of the Sun The prograde or retrograde motion of the planets is because of Earth’s motion

21. The Copernican Model SUN SUN PERFECTLY CIRCULAR ORBITS

22. Copernicus’ motivation a note at the beginning of the book: theory contained therein was not meant to actually model reality, merely an easier mathematical formulation equally spaced planets in circular orbits would represent harmony in the universe

23. Copernicus’ System His system was only slightly less complicated than Ptolemy’s Could not explain changes in the brightness of Venus

24. Copernicus’ System Not the revolution, but the spark First to create a complete and general system, combining mathematics, physics, and astronomy Not yet understood: the further the planet was from the Sun, the longer it takes to orbit

25. The Church’s reaction Ignored at first as purely theoretical Objected to the removal of the Earth from the center of the universe. Correction of an established theory proved that scientific investigation was a threat to authority Copernicus’ book was banned in 1616 Don’t be bringing that noise around here!

26. Copernicus Questions What are the contributions to astronomy made by Copernicus? First to apply physics and mathematics to astronomy Reawakened heliocentric idea Why did Copernicus come up with his theory? It was more pleasing to his mind Made more sense