1. Today! From Earth’s Perspective: Lunar Motion A Brief History of Astronomy

2. Lunar motion: tidally locked--gravity makes same side (with a displaced core) always face earth. Synodic period--29.5 days --cycle of phases. --Length of day on the moon. --Lunar phases--see diagrams. Siderial period--27.3 days --with respect to stars.

6. Brief History of Astronomy: 5,000 BC--Sumerians--astrology and '12th planet'? 2,500 (or 8,500) BC--sphinx and great pyramid. 1,600 BC--Babylonians--star and planet tables. 1,500 BC (or much earlier)—Hindus --cycles of cosmos and lifetime of sun. 500 BC--Pythagoras--earth and heavens spherical. 350 BC--Aristotle--physics of forces, geocentric universe. 250 BC--Aristarchus--first sun-centered system. 200 BC--Erastosthenes--accurate size of earth. 130 BC--Hipparchus--epicycle, precession, charts. 7 AD?--Wise men tracked the Christmas star --Saturn conjunct Jupiter? 125 AD--Claudius Ptolemy--accurate geocentric model. 400 AD Hypatia and the Fall of the Alexandrian Library

7. 5,000 BC--Sumerians--astrology and '12th planet'? Nibiru? Zecharia Sitchin

8. 2,500 (or 8,500) BC--sphinx and great pyramid.

9. 1,600 BC--Babylonians--star and planet tables. The Babylonian zodiac was sidereal, i.e. longitudes were not measured from the vernal equinox (the intersection with the celestial equator), but from a small number of bright fixed stars near the ecliptic. The most important reference stars appear to have been Aldebaran (defining 15º Taurus), Pollux (0º Cancer), Regulus (5º Leo), Spica (0º Libra), Antares (15º Scorpius) and Deneb Algedi (0º Aquarius).

10. 1,500 BC (or much earlier)—Hindus --cycles of cosmos and lifetime of sun. Hindu CycleAncientModern yuga24,000 yrs25,800 yrs, precession manvantara308 mill. yrs225 mill.yrs., galactic year Lifetime of sun8.6 bill. yrs8.8 bill. yrs., using nuclear physics

11. 500 BC--Pythagoras--earth and heavens spherical.

12. 350 BC--Aristotle--physics of forces, geocentric universe.

13. First sun-centered system.

14. 200 BC--Erastosthenes--accurate size of earth.

15. 130 BC--Hipparchus--epicycle, precession, charts.

16. 7 AD?--Wise men tracked the Christmas star --Saturn conjunct Jupiter? Painting by Giotto: Christmas star as Halley’s comet?

17. 125 AD--Claudius Ptolemy--accurate geocentric model of universe

18. 400 AD Hypatia and the Fall of the Alexandrian Library