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Our Moon!

Our Moon!. …done that…). (Been there…. Crew of Apollo 11 : First Astronauts to Walk on the Moon !. (Really… we have been there!). A Highly Trained, Professional Lunatic. ( P.S. : Our Moon = “ Luna ”). “ The Moon ”: A great place for golfing?. (Alan Shepard, Apollo 14).

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Our Moon!

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  1. Our Moon! …done that…) (Been there…

  2. Crew of Apollo 11: First Astronauts to Walk on the Moon!

  3. (Really… we have been there!)

  4. A Highly Trained, Professional Lunatic (P.S.: Our Moon = “Luna”)

  5. “The Moon”: A great place for golfing? (Alan Shepard, Apollo 14) No, too many divots…

  6. How Craters are Made (…obviously…)

  7. Some nice craters …Named after scientists, mountains, “seas of storms” (Mare Imbrium)…

  8. A “Man in the Moon”? (…No, I’ve never really seen it, looking up in the sky…)

  9. Many Lunar Craters = scars from “Heavy Bombardment” period in the early Solar System…! Even the ejected pieces (“tektites”) from old craters, have their own new “craters”! Older surfaces  More Heavily Cratered!

  10. But where does the Moon come from? • Our Moon was formed by a collision! • (…we think…) • Within the first ~50 Million Years (or so) • of the Solar System’s history, • a ~Mars-sized object hit the Earth… (Numerical Simulation) (Video) http://vimeo.com/15610496

  11. How do we knowthat our Moon was formed by a collision? • …just like good (bad?) pizza, our Moon is mostly crust! • Similar to Earth’s crust, that is. • (Plus hints from its isotopic composition, fast angular momentum…)

  12. Phases of the Moon

  13. The Cycle of Lunar Phases (Depending upon the positions of the Sun, Moon, Earth, and the Observer…) Moon-Rise/Set times for different phases:

  14. What exactly is a “Month”, anyway? Sidereal Month (“by the Stars”) vs. Synodic Month (“by the Phases”)

  15. What is a “Blue Moon”? • The term blue moon originates in folklore. • One “lunation” (an average lunar cycle) is 29.53 days. • Therefore, 12.37 lunations occur in a solar year. • Different traditions place the “extra" blue full moon at diff. times: • The Maine Farmers' Almanac– An extra full moon in a season. • One season was normally three full moons. • If a season had four full moons, • then the third full moon was called a blue moon. • In calculating the dates for Lent and Easter, the Christian clergy identified a Lenten moon. • Historically, when the moons arrived too early, they called the early moon • a betrayer (belewe) moon, so the Lenten moon came at its expected time. • Folklore named each full moon according to its time of year. A moon that came too early was • called a blue moon; the rest of the moons that year retained their customary seasonal names. • The second full moon in one calendar month is sometimes called a blue moon. • This usage results from a misinterpretation, in the March 1946 issue of Sky and Telescope, • of the traditional definition of blue moon. Blue moon of Dec. 31, 2009, with partial lunar eclipse

  16. Eclipses! “Lunar” & “Solar”

  17. The Corona (“crown”) of the Sun Viewable only during a Total Solar Eclipse:

  18. Why No Eclipse every month?

  19. Only get Eclipses when Luna is in the “Ecliptic Plane”! (… well, Duh! ...)

  20. “Tidal Forces”: Any Uneven, Stretching Gravitational Pull! (Ex: Luna creating Earth’s Ocean “Tides”!)

  21. “Syzygy”! Do the Sun & Moon work together to make stronger tides? (…sometimes yes, sometimes no…)

  22. Tidal “Friction” #1: “Tidal Locking” of Luna into Synchronous Rotation about Earth!

  23. Two very different sides of our neighbor, Luna: Near Side (always seen) Far Side (never seen!)

  24. Great Music… …Bad Astrophysics!

  25. (…from the solid Earth bulging ~tens of cm each high tide…) Tidal “Friction” #2: • “Tidal Braking” slows Earth’s daily rotation about its axis! • Earth experiences Longer Days! • Conservation of Angular Momentum… • Causes Lunar orbit to spiral out, farther & farther • away from Earth! (No more Total Solar Eclipses!)

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