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Length of the Seasons Venus Transit June 8th, 2004 The Universe

Length of the Seasons Venus Transit June 8th, 2004 The Universe. Dr. Scott Schneider Friday April 23 rd , 2004 Presentation for National Astronomy Day (technically 04/24/04) Webpage : http://www3.ltu.edu/~s_schneider/astro/astroday_2004.shtml. Lengths of the Seasons change.

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Length of the Seasons Venus Transit June 8th, 2004 The Universe

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  1. Length of the SeasonsVenus TransitJune 8th, 2004The Universe Dr. Scott Schneider Friday April 23rd, 2004 Presentation for National Astronomy Day(technically 04/24/04) Webpage : http://www3.ltu.edu/~s_schneider/astro/astroday_2004.shtml

  2. Lengths of the Seasons change • Earth orbit is “drifting” around the Sun • Precession of orbit • Caused by pull from planets and Moon • Close/Far points in orbit move • We adjust calendar with leap days • To prevent snow in July! • But duration of seasons oscillate

  3. How to find your way in the Solar system : • All planets go around the Sun • also, in the same “direction” • Define reference plane as Earth-Sun • Called the ECLIPTIC • All other planet orbits tilted, relatively • Venus has an orbit tilt of about 30 • Save this info for later!

  4. Seasons vs. Aphelion/Perihelion • Spring defines quadrants • Quadrants near Aphelion are longer in time • Perihelion and Aphelion drift – so season lengths change

  5. Season duration – short time scale • Currently Spring/Summer are longer • But, Spring duration shrinking .. Fall rising!

  6. Season duration – long time scale • Winter longest before –4000 (shortest ~3500)

  7. Follow Spring Equinox Date (wide) • Spike around 1600? – Gregorian Reformation!

  8. Follow Spring Equinox Date (med) • Small shifts at 100, none at 2000, 2400, 2800??

  9. Follow Spring Equinox Date (zoom) • Slow drifting of the date later in March

  10. More info on seasons? http://www3.ltu.edu/~s_schneider/astro/seasons.shtml (Unlinked to show the underscores …) http://www3.ltu.edu/~s_schneider/astro/seasons.shtml

  11. What is a transit? • Planet crosses the face of the Sun • Mercury and Venus = closer to the Sun • occasionally pass between Earth + Sun • Transit of Earth for the Moon? • Lunar eclipse • Transit of the Moon seen by the Earth? • Solar eclipse!

  12. Features of Venus Transits • Nearly circular orbit • Transits at each node in equal numbers • Mercury : Less often in May than November • Moving faster in orbit in May • Only seen from part of the Earth • Usually a whole hemisphere • Sometimes “grazing” – only part of hemisphere • 243 year cycle (with 8 year and ~ 100 shifts) • Venus “large” enough to see “naked” eye • Must use eclipse glasses or protected scope!

  13. Rarity of Venus Transits? • Between –2000 and 4000 – only 81 • No human alive has seen one (1882) • Transit of 1631 predicted by Kepler • But not seen! • Currently occurs in June or December • Usually occur in pairs – 8 years apart • Because 13 revolutions of Venus ~ 8 of Earth • Another period of ~105-110 years • Strong period of 243 years (forms “series”)

  14. Historical notes of Transits • Mercury ~ 1/158 to 1/195 of Sun’s disk • Not seen without a telescope! • Venus ~ 1/31 to 1/32 of Sun’s disk • Visible w/o telescope (but with FILTER!) • Venus transits widely observed in late 1700’s and 1800’s

  15. Ecliptic plane - Today • Oriented by Seasons (Spring = pivot) • Venus orbit = Blue = above … Green = below (nodes) WINTER SPRING FALL SUMMER

  16. Ecliptic plane – at Transit • Oriented by Seasons (Spring = pivot) • Venus orbit = Blue = above … Green = below (nodes) WINTER SPRING FALL SUMMER

  17. Right place - Right time! • Venus makes more orbits than Earth • Often passes those crossing points (nodes) • But, Earth isn’t always there to see it! • One “face” of the Earth gets best view • Transit is at most ~ 8 hours • Short time scale - not a good match • Wait many years, orbits match nicely!

  18. What does “a pass” mean? • Nov/Dec transits - lower left to upper right • May/June transits upper left to lower right • As the “cycle” advances, individual passes will move either “up” or “down” relative to the center of the sun • A “series” would be a set of passes

  19. How would a “series” look? Full Series “B” 243 Year period

  20. What about a “pair”? 8 year jump between consecutive series

  21. Can I investigate the transits myself? Sure! Here is the website for my very first home-grown Java applet – the Venus Transit applet! http://www3.ltu.edu/~s_schneider/astro/transits/venusjava.shtml (Unlinked to show the underscores …) http://www3.ltu.edu/~s_schneider/astro/transits/venusjava.shtml

  22. Tuesday, June 8th, 2004 Great prediction webpage : http://sunearth.gsfc.nasa.gov/eclipse/transit/TV2004.html • Circumstances for Detroit: • Sunrise 05:54 AM (Venus past midpoint of transit) • Venus rises a few minutes later (tip of sun = “sunrise”) • Venus touches inside edge of sun (on way out) = 7:05 AM at 11 degrees above the horizon • Venus touches outside edge = 7:25 AM at 140 alt • Possible trip to Metro Beach MetroPark? • (Better view of sunrise) • Wear your glasses!!

  23. But can we really see it? Luckily, we have a sunspot today (04/23/04) – it is a little smaller .. and we can see IT!

  24. References Jean Meeus – TRANSITS – Willmann-Bell Jean Meeus is an Astronomer from Belgium – does some absolutely amazing astronomical calculations. Has three other excellent books : Astronomical Algorithms Astronomy Morsels More Astronomy Morsels

  25. What about Marvin? He wanted to blow up the Earth because it blocked his view of Venus!

  26. Conditions for blocking .. • How often does Earth block Venus? • Calculate the location where the Venus-Mars line crosses the ecliptic – if the Earth is there also – block!

  27. After the computer pulled a few all-nighters … From the year 1000 to 3000 … Onlyonetime = Nov 8th, 2746 ~ 7:45 pm

  28. Conclusion … Marvinis just a big foo-foo head!!

  29. Last but not least …The Universe! • Logarithmic distance scale (y axis) • Need strong kung-fu math to squash the distance scale of the Universe! • “Hour angle” (right ascension) (x axis) • Measured from “Spring” event – (line in space) • 360 degrees = 24 hours • The Universe on the Second Floor! • Much more info here : • http://www.astro.princeton.edu/~mjuric/universe/

  30. Astro Wall Volunteers • James Mason * • Clark Adamczyk * • Steven R Moberly * • George Swan * • Lindsay Zaremski • Adrian Brdarski • Jeremy Dunaj • Judy Sullivan (Custodian) – Cleaner of the Solar System! These students helped me put little dots on the wall, and big giant strips of tape. * Members of LTU’s first undergraduate Astronomy course

  31. This talk, and other exciting things can be found … http://www3.ltu.edu/~s_schneider/astro/index.htm Thank you, Good Night, Drive Safely!

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