Motions in the Sky

1. Motions in the Sky Watchers and Timekeepers

2. The Milky Way over Utah

3. Felix Shih’s work

4. The First Science • Unless you were a troglodyte* thousands of years ago, you couldn’t help but notice that the sky changed, hour by hour, day by day, month by month, year by year *someone who lives underground

5. The Sun rose and set and sometimes even disappeared; • The Moon also rose and set, changed shape, and occasionally turned red; • There were patterns in the night sky that came into view at different times of the year; • There were stars that defied the patterns and marched recklessly across the sky; • And there were often visitors in the heavens.

6. Astrologers: precursors to Astronomers • As in any population, there were a few geeks who took great interest in what was happening in the sky • These people never knew the cause of the events and phenomena they observed, but they did keep track of their periodicities • And they were good storytellers!

7. Great mysticism was attached to the goings-on in the sky • The people who recognized the repetition of celestial events and could make predictions of the next occurrence were therefore seen as shamans • Shamans in a society wield great power • The ability to predict phenomena in the sky extended back down to Earth and the supposed ability to foresee the future • Often for personal gain!

8. Time • Since celestial events happen with a regularity, the shaman astrologers could use this periodicity to construct calendars (coming up in a minute) • Even today our calendars are closely attached to Astronomical phenomena • But it took millennia to iron out all the kinks

9. Months and Years • The most obvious cyclic events in the sky are the rising and setting of the Sun and the Moon • Important to realize is the fact that these rising and settings vary from day to day • Also critical is to understand that the Sun and the Moon cycles are not connected

10. The Sun rises in a different place every day

11. These four special days mark out many calendars

12. They are: Winter Solstice, Vernal Equinox, Summer Solstice, Autumnal Equinox

13. Northern Hemisphericocentric* • The Southern Hemisphere has equivalent days • The Sun’s rising position changes over a year, from south of East in December to directly east in March to north of East in June and back to East in September • And all points in between • Same all year long on the equator *not a real word

14. Effects • This changing rise position is caused by the tilt of the Earth relative to the Sun and by the motion of the Earth around the Sun • The tilt is what causes the Seasons* • Ancient astrologers did not know about the tilt or the orbit, but they knew the cycle repeated after about 365 days *discussed in another ppt

15. Analemma • Not a regular path in the sky • Left: each picture was shot on a different day but at the same time over a year

16. Important Days • The four Astronomically important days delineated the four Seasons, although some cultures like the ancient Egyptians recognized only three • Please realize that ancient peoples did not necessarily have a December, March, etc., but the two solstices and the two equinoxes were recognized nonetheless

17. The Moon • Less ‘well-behaved’ than the Sun • Rises in different places and much different times every night, if it was visible at all • Changed shape as well, unlike the unchanging Sun

18. Phases • The Moon appears to change shape because of its position relative to the Earth and the Sun • In the bottom right there seems to be a problem; the Moon is there however! • The cycle takes about 29 days, an interval known to the ancients

20. Calendars (snapshots, only for comparison) • Egyptian • 360 + 5 days • Sothis • 3 seasons • 3 10-day weeks • Babylonian sexigesimal system • 360 days, 12-30 day months, 4 seasons • Begins with crescent Moon

21. Greek • 4th C. BC • Months 1-4 36 days, 5-10 35 days each • Roman (Julian) • 12-month 355 day year • D days per month • MensisIntercalaris month of 27 days • Chinese • 12 Lunar months with alternating names • Mayan • Many variants that synchronized, e.g. 260 day Tzolkin with 365 day Haab • Also lunar and Venusian cycles

22. Modern Western • Established by Pope Gregory 1582 • Threw out lunar influence (almost) • 365.24 days • Leap year rules • Still corrected for atomic clocks

23. Days of the Week • Like calendars, each culture had different names for the days of the week, number of days in a week, and number of hours in a day • Western names derive from celestial objects • English names span several languages

24. Sundials • The oldest known instruments for keeping track of time • First attempt at marking time ~ 5000 BC • 2500 BC: Babylonian and Egyptian obelisks • By 250BC the Greeks produced complex and more accurate sundials using their knowledge of geometry

25. Examples

26. Patterns in the Night • Constellations: “stars together” • Different for different cultures (following slides) • Fanciful at best, but a good mnemonic to find things • Useful for calendars

27. Special Constellations • Zodiacal • 12 Astrological signs • Misleading: the sign is not up at night during its reign • Circumpolar • Never set • Useful for navigation

28. Two Western Constellations Orion is facing backwards for use with a celestial sphere

29. Egyptian Sky (interpretation of Greek view)

30. African Sky • Used the sky to explain myths

31. Chinese star map from the Tang Dynasty

32. Visitors in the Sky • The First UFOs! • Unpredictable, irregular • Shooting Stars • Not! Small grains of dust • Comets • “Bad Star”: Dis-Aster • Harbingers of catastrophe

33. Why Astrology is Not a Science • Vague, untestable • No account for time delay • Wide constellations • Twins

34. Which Horoscope is “Real”? You have a relentless drive to get at the heart of things this Tuesday, whatever is under the surface or behind the scenes. Emotionally, you are also hot stuff, rushing into areas and handling subject matters that others would never come near. You may not like displays of emotion and pushy people, or at least find them challenging and thought-provoking. There is not much to slow your progress, however, and by this afternoon you are moving forward with your professional activities at full speed ahead. This evening is a good time to have a long talk with your partner about your future plans. You have a good sense of where you stand in a group of people; exploit this at your gatherings this week. Nonetheless, your tendency to try to control any situation can get out of hand so rein in your urges in this area. There are those people who try to stand in your way, but they can be ready allies if you just give them a chance. Look to your social network resources to make this happen. Financially you should be conservative this week, but emotionally be liberal. By Friday your growing relationship will seem more stable and long-lasting. Listen to your best friend’s advice in these matters; it will be sound counsel.