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

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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_20
04.shtml
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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

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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!

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Seasons vs. Aphelion/Perihelion

• Spring defines quadrants
• Quadrants near Aphelion are longer in time
• Perihelion and Aphelion drift so season lengths
  change

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Season duration short time scale

• Currently Spring/Summer are longer
• But, Spring duration shrinking .. Fall rising!

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Season duration long time scale

• Winter longest before 4000 (shortest 3500)

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Follow Spring Equinox Date (wide)

• Spike around 1600? Gregorian Reformation!

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Follow Spring Equinox Date (med)

• Small shifts at 100, none at 2000, 2400, 2800??

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Follow Spring Equinox Date (zoom)

• Slow drifting of the date later in March

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More info on seasons?

• http//www3.ltu.edu/s_schneider/astro/seasons.sht
  ml
• (Unlinked to show the underscores )
• http//www3.ltu.edu/s_schneider/astro/seasons.sht
  ml

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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!

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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!

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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)

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Historical notes of Transits

• Mercury 1/158 to 1/195 of Suns disk
• Not seen without a telescope!
• Venus 1/31 to 1/32 of Suns disk
• Visible w/o telescope (but with FILTER!)
• Venus transits widely observed in late 1700s and
  1800s

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Ecliptic plane - Today

• Oriented by Seasons (Spring pivot)
• Venus orbit Blue above Green below (nodes)

WINTER
SPRING
FALL
SUMMER
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Ecliptic plane at Transit

• Oriented by Seasons (Spring pivot)
• Venus orbit Blue above Green below (nodes)

WINTER
SPRING
FALL
SUMMER
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Right place - Right time!

• Venus makes more orbits than Earth
• Often passes those crossing points (nodes)
• But, Earth isnt 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!

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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

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How would a series look?
Full Series B 243 Year period
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What about a pair?
8 year jump between consecutive series
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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/ve
  nusjava.shtml
• (Unlinked to show the underscores )
• http//www3.ltu.edu/s_schneider/astro/transits/ve
  nusjava.shtml

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Tuesday, June 8th, 2004
Great prediction webpage
http//sunearth.gsfc.nasa.gov/eclipse/transit/TV2
004.html

• Circumstances for Detroit
• Sunrise 0554 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)
  705 AM at 11 degrees above the horizon
• Venus touches outside edge 725 AM at 140 alt
• Possible trip to Metro Beach MetroPark?
• (Better view of sunrise)
• Wear your glasses!!

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

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After the computer pulled a few all-nighters
From the year 1000 to 3000
Only one time Nov 8th, 2746 745 pm
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Conclusion
Marvin is just a big foo-foo head!!
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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/

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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 LTUs first undergraduate Astronomy
course
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This talk, and other exciting things can be found

• http//www3.ltu.edu/s_schneider/astro/index.htm

Thank you,
Good Night,
Drive Safely!