solstice pole

Discussion in 'Astronomy, Exobiology, & Cosmology' started by sculptor, Mar 20, 2023.

  1. sculptor Valued Senior Member

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    I read that if you have a vertical pole, the shadow at the tip of the pole shadow cast by the sun will trace a line from true west to true east during the solstice.
    So, the pole was placed on the deck, and I am occasionally going out and marking the tip of the shadow.

    Do you believe that the end result will be a line running due east to due west?
     
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  3. exchemist Valued Senior Member

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    Not unless you are at the equator.
     
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  5. DaveC426913 Valued Senior Member

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    Well, it's not going to be a straight line, so it will be pretty tricky to extrapolate to the horizon.
     
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  7. foghorn Valued Senior Member

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    T0day is the Spring Equinox, so do you mean 'Equinox pole'.
    This link has a video clip of the shadow of the top of the pole moving along a west to east line.
    https://earthsky.org/human-world/equinox-shadows-trace-a-straight-line/

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    Sculptor, the third from last picture on the link, has a wall mounted pinhole sundial. Have a go at making one if you have the space and a south facing wall, I don't.
     
    Last edited: Mar 20, 2023
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  8. foghorn Valued Senior Member

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    reply to my own post...
    Foghorn, that's not a real all day sundial on the wall, it only records the noon position of the sun throughout the year.
     
  9. foghorn Valued Senior Member

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    Thank you Foghorn.
     
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  10. gmilam Valued Senior Member

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    Solstice or equinox?

    Anyway, I have read that if you mark the end of the shadow of the vertical pole in the morning, and the end of the shadow in the evening. Then draw a straight line between the two points, the point in that line that is closest to the the base of the pole is due north of the pole... in the northern hemisphere. This is supposedly true any day of the year, not just on a solstice or equinox.
     
  11. exchemist Valued Senior Member

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    Aha, now I understand. That's interesting.
     
  12. sculptor Valued Senior Member

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    Yeh----OOPs---thanx---
    I was distracted dealing with slow motion medical personnel---trying to get an appointment to have a possible cancerous(?) tumor examined----
    Equinox pole
    (actually a 1/2 inch dowel held upright in a vice grip)(but it worked)
    and the line was straight---based on about 15 data points
    ok
    so east and west line is now painted on my deck
    (could come in handy(?))

    fun anyway
     
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  13. DaveC426913 Valued Senior Member

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    Cool way to do it.

    When I landscaped my front yard, I used Google maps to plot the cardinal directions. I made the entire yard into a giant hardscaped 8-point compass rose. All paths, steps and raised flower beds were offset from the property lines by the appropriate 19 degrees. Even the arbor I scratch-built was skewed by 19 degrees.

    (Tree belongs to city, so I had to make my whole design around it.)

    I went with the compass rose because it is an important component of both sailing and scuba diving.

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    Last edited: Mar 21, 2023
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  14. Neddy Bate Valued Senior Member

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    One of my neighbors has this painted on the front of their house:

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    And the sidewalk does run west-to-east, just as their compass shows.

    Where I am, just about every street is a straight line that runs east-west or north-south. Traveling east early this morning, I had the sun directly in front of me, blinding me. I'll be traveling west later, around twilight, and expect the same thing for the return trip.
     
  15. DaveC426913 Valued Senior Member

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    Well, after thirty years, the City came today and chopped that tree down and turned it into sawdust*.

    *well, the carpenter ants did that. The City just finished the job.
     
  16. DaveC426913 Valued Senior Member

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    Yeah. I've lived on the West side of my city's downtown for 30 years and occasionally envy the East-enders who have the sun behind them for both the trip in and the trip home.
     

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