ANNOUNCEMENTS. HOMEWORKS #4 & #5 handed out today. HAND HW#4 IN FOR CREDIT NEXT THURSDAY

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1 ANNOUNCEMENTS HOMEWORKS #4 & #5 handed out today. HAND HW#4 IN FOR CREDIT NEXT THURSDAY OPTIONAL Dark Sky Field Trip next Tuesday 6:15pm meet at Fiske dress very warmly. Pray for clear weather. IF YOU WISH HAND-in #5 NEXT THURS TO REPLACE POOREST GRADE ON PREVIOUS HWs. Material from BOTH HWs will be covered on the Midterm Exam Midterm exam 1.5 weeks from today in TUESDAY S class on OCTOBER 13 th in BESC 180. OPTIONAL Observing night at SBO next Monday 7:30pm. OPTIONAL ERATOSTHENES CHALLENGE HELP SESSION next Monday 2 4 pm or next Tuesday GATE #5 Folsom Field

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3 Eclipse video with possibly offensive language (my mother would have been offended; my son would not) will be shown in first 10 minutes of class period on Tuesday. Come late if you wish.

4 For how long have Humans had the ability to predict ECLIPSES of the Sun and the Moon? Could all eclipses have been predicted in ancient times?

5 The Battle of Halys took place at the river Halys in Turkey) on May 28, 585 BCE between the Medes and the Lydians. A Solar Eclipse occurred, was viewed as an omen from the gods and the war was ended! First known Solar Eclipse prediction by Thales of Miletus.HOW DID HE DO IT??? Subsequently the Lydians and the Medes drew up peace accords. Only a few dozen Solar Eclipses are mentioned throughout antiquity these events are RARE in any portion of the world. AND YET ANCIENT PEOPLE KNEW HOW TO PREDICT ECLIPSES!!! *** this is why I want you to know what appears to be obscure details of the lunar orbit called LUNAR STANDSTILLS ***

6 BECAUSE FULL MOON IS ALWAYS NEARLY EXACTLY OPPOSITE TO THE SUN (FULL MOON RISES WHEN SUN SETS) IT ALSO SWINGS NORTH AND SOUTH DURING THE YEAR BUT OPPOSITE TO THE SUN S SWING: e.g., THE MIDWINTER FULL MOON IS THE HIGHEST IN THE SKY, RISES AND SETS FURTHEST NORTH OF EAST AND WEST & IS UP THE LONGEST!! BEAUTIFUL.

7 ECLIPSE SEASONS: TWICE PER YEAR WHEN SUN IS NEAR THE LOCATION OF ONE OF THE TWO NODES ECLIPSE SEASONS WOULD ALWAYS BE AT SAME TIME OF YEAR except LUNAR ORBIT TWISTS IN SPACE MOVING NODES BACKWARDS (19 DAYS PER YEAR!!) Moon s path NODE S PATH

8 Lunar Orbit not stable. Nodes & standstill points move through the zodiac backwards Why would we care about these Standstill points? Nodes are where eclipses occur Nodes are invisible and cannot be directly observed or tracked. Standstills are 90 degrees away from the nodes. In the year of a Lunar Standstill eclipses happen close to the equinoxes. Eclipse prediction!

9 EXTREMES OF THE LUNAR ORBIT Because the Moon s orbit is titled with respect to the ecliptic plane, the Moon sometimes gets up to 5 degrees NORTH of the ecliptic or up to 5 degrees SOUTH of the ecliptic. But for the Full Moon these extremes happen only once every 9.5 years (a northern extreme in winter is followed 9½ years later by a southern extreme for the Full Moon nearest the summer solstice). FULL CYCLE OF STANDSTILLS IS 19 YEARS (closest even number to the 18 and two-thirds year cycle of the nodes. These extremes are called: MAJOR LUNAR STANDSTILLS IN ANALOGY WITH SOLSTICES, EXTREME LOCATIONS OF THE SUN.

10 AN ECLIPSE HAPPENS AT THE FULL MOON CLOSEST TO THE SOLSTICE IN THE YEAR DEPICTED AT CENTER ABOVE. OTHER YEARS ECLIPSE SEASONS ARE AT OTHER TIMES Eclipse season at solstices NOTE WELL: THE ABOVE SKETCH IS QUITE SMALL IN COMPARISON TO THE SKETCHES AT LEFT. THE FULL EXTENT ABOVE IS ONLY A BIT OVER TWO THUMB LENGTHS IN THE SKY!!!

11 NOTE WELL: THE ABOVE SKETCH IS QUITE SMALL IN COMPARISON TO THE SKETCHES AT LEFT. THE FULL EXTENT ABOVE IS ONLY A BIT OVER TWO THUMB LENGTHS IN THE SKY!!! AN ECLIPSE HAPPENS AT THE FULL MOON CLOSEST TO THE SOLSTICE IN THE YEAR DEPICTED AT CENTER ABOVE. OTHER YEARS ECLIPSES SEASONS ARE AT OTHER TIMES

12 NOTE WELL: THE ABOVE SKETCH IS QUITE SMALL IN COMPARISON TO THE SKETCHES AT LEFT. THE FULL EXTENT ABOVE IS ONLY A BIT OVER TWO THUMB LENGTHS IN THE SKY!!! AN ECLIPSE HAPPENS AT THE FULL MOON CLOSEST TO THE SOLSTICE IN THE YEAR DEPICTED AT CENTER ABOVE. OTHER YEARS ECLIPSES SEASONS ARE AT OTHER TIMES

13 AT SOLID LINE IN CENTER, FULL MOON IS ON THE ECLIPTIC AND AN ECLIPSE OCCURS, ONCE EVERY 9 YEARS A LUNAR ECLIPSE OCCURS on THE FULL MOON NEAREST THE SOLSTICE FULL CYCLE OVER A 18 ½ - 19 YEAR PERIOD next one: June 2025 last one: early July 2015

14 AT SOLID LINE IN CENTER, FULL MOON IS ON THE ECLIPTIC AND AN ECLIPSE OCCURS, ECLIPSE SEASONS NEAR SOLSTICES ONCE EVERY 9 ½ YEARS A LUNAR ECLIPSE OCCURS on THE FULL MOON NEAREST THE SOLSTICE ECLIPSE SEASONS NEAR EQUINOXES ECLIPSE SEASONS NEAR EQUINOXES

15 ECLIPSES POSSIBLE ONLY TWICE PER YEAR DURING ECLIPSE SEASONS WHEN FULL & NEW MOONS OCCUR CLOSE TO THE NODES In the year of a lunar standstill (either major or minor ), the Eclipse Seasons are near the equinoxes

16 ECLIPSE NUMEROLOGY: AN INTRODUCTION ECLIPSE SEASONS : The possibility for one or more eclipses happens twice per year when Full and/or New Moon occurs in or near the Lunar Nodes. Because nodes move backwards around the Moon s orbit, these eclipse seasons are LESS THAN ½ year apart: 173 DAYS to be exact. ECLIPSE SEASONS MOVE BACKWARDS through the calendar at a pace of about 19 days per year eclipse seasons are ~ 19 days earlier than the previous year. ECLIPSE SEASONS CYCLE THROUGH THE CALENDAR ONCE EVERY 9 ½ YEARS or TWICE IN 19 YEARS ( YEAR OF METON )

17 NOTICE AT LEFT PROGRESSION OF SPRING ECLIPSE SEASON: 1984 end of May 1985 beginning and mid May 1986 mid April 1987 late March 1988 mid March (year of a lunar standstill)

18 STONEHENGE: TEMPLE OR OBSERVATORY? EARLIEST CONSTRUCTION c BCE

19 STONEHENGE: STONEHENGE A MONUMENT CONSTRUCTED IN STONE AGE BRITAIN BUT BY WHOM AND WHY??? 90 MILES SW OF LONDON ON SALISBURY PLAIN AT THE INTERSECTION OF 2 HIGHWAYS. SURROUNDED BY BARROW DOWNS (ANCIENT GRAVES)

20 circa 3200 BCE circa 2500 BCE Circa 2400 BCE INTERESTINGLY THERE WERE SEVERAL BUILDING PERIODS AT THIS SITE. LATEST DATES SUGGEST STONEHENGE 1 WAS ERECTED PRIOR TO 3000 BCE, OVER 5000 YEARS AGO! STONEHENGE 1 MORE INTERESTING ASTRONOMICALLY STONEHENGE 3 MORE INTERESTING FOR ITS ENGINEERING.

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22 THE HEELSTONE SUMMER SOLSTICE SUNRISE BACKSIGHT FORESIGHT AT CENTER OF SARCEN CIRCLE

23 STONEHENGE 1 STONEHENGE 2 & 3 (c BCE) (c BCE) AVENUE + DITCH MASSIVE STONES including 56 HOLES FILLED WITH CHALK 5 TRI-LITHONS, SARSEN FEW LOCAL STONES CIRCLE & BLUESTONES

24 ONE OF 56 AUBREY HOLES EVENLY SPACED AROUND 3OO FOOT DIAMETER CIRCLE

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26 REASONS WHY STONEHENGE 1 WAS LIKELY AN ECLIPSE PREDICTOR: AUBREY HOLES: 56 = 18 2/3 X 3 (three times the period of the nodes). The Classical World s Year of Meton 2. Stonehenge 3 Rectangle accurately aligned with solstices and standstills to ± ½ degree. Stonehenge 1 circle is larger and so accuracy is better: ± ¼ degree! (size of Sun and Moon in sky ½ degree Stonehenge 1 accuracy good enough to predict all eclipses. 3. Stonehenge Rectangle (summer solstice sunrise and full moon rise at major standstill in perpendicular directions only within ± 150 miles of Stonehenge. THE EVIDENCE FOR ECLIPSE PREDICTION IS CIRCUMSTANTIAL but RELIES ON: NUMEROLOGY: NUMBER 56 RELATED TO LUNAR NODE CYCLE AND HAS NO OTHER OBVIOUS CYCLES OR USE GEOMETRY: ALIGNMENTS WITH EXTREME POSITIONS OF BOTH THE SUN AND THE MOON EXTREMES OF MOON GIVE LOCATIONS OF NODES!

27 THE STONEHENGE RECTANGLE Only at the latitude of Stonehenge are the summer solstice sunrise point and the summer solstice Full Moon rise (at standstill) exactly perpendicular. Already present in Stonehenge 1. evidence for eclipse prediction c BCE 56 Aubrey Holes date to Stonehenge 1. (56 = 18 2/3 x 3 exactly 3 times the cycle of the nodes)

28 THEORIES ABOUT STONEHENGE CONTINUE TO ABOUND!!

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30 NOTICE AT LEFT PROGRESSION OF SPRING ECLIPSE SEASON: 1984 end of May 1985 beginning and mid May 1986 mid April 1987 late March 1988 mid March (year of a lunar standstill)

31 SHORT ECLIPSE SERIES IN BETWEEN SKIPS (NO ECLIPSE)