1. Announcements
Let me know the book you want to do your 1st project on as soon as you decide. First-come-first-served with no duplication allowed.
The first Dark Sky Observing Night is next Tuesday night (2/6). Activities start at 7:30 so set-up begins at 6:30.

2. Chapter 2 Astronomy in Antiquity
Ptolemy and the Earth centered universe

3. Babylonian Chaldean Tablet

4. The Enuma Anu Enlil was a compilation of bad omens

5. By observing over centuries the Babylonians could detect cycles

6. Babylonian Number System

7. Babylonian Calendar

8. The Metonic Cycle was one of the cycles they observed
235 lunar cycles = 19 solar cycles +7 so add seven intercalary months every 19 years to “even” it out

9. Egyptian culture was centered on the annual flooding of the Nile
Thus the year is divided into three seasons: the Flood, the Subsiding and the Harvest

10. Egyptian Calendars
The lunar calendar had “intercalary” months inserted occasionally to keep synchronized with the seasons
The administrative calendar had 365 days in every year
Calendars were “synched” with the helical rising of Sirius

11. The Greeks
Aristotle
Plato
Aristarchus

12. Eratosthenes
His value of the circumference of the Earth of 250,000 stadia is probably not far off.

13. The Spheres of Eudoxus

14. Plato and the requirement of circles and spheres

15. Aristotle and Physics

16. Aristotle defined two types of motion: natural and forced
The motion of an arrow through the air is a forced motion. The force is originally applied by the bow and then by the air
Falling bodies were a natural motion. The more massive something is, the faster it will fall.

17. After Alexander the Great, Greek astronomy became more “precise”
Post-Alexander, Aristarchus attempted to measure the distance to the Sun by measuring the Earth-Sun-Moon angle at quadrature
The Spheres of Eudoxus worked OK for the Moon but were way off for the planets

18. Appolonius was the first to propose the eccentric and epicycle

19. Hipparchus made it a model capable of prediction

20. Hipparchus also measured stellar positions precisely enough to discover the Precession of the Equinoxes

21. Hipparchus also modeled the changing speed of the sun

22. Ptolemy built on Hipparchus’ work and added the Equant

23. The Complete Ptolemaic System

24. The Almagest was THE book on astronomy for almost 1500 years
Originally titled “Megale Syntaxis” later known as the “Greatest Compilation”