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Old 02-17-2023, 10:01 AM
 
Location: The Driftless Area, WI
7,102 posts, read 4,915,886 times
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Quote:
Originally Posted by Northern Maine Land Man View Post
Back in the day, every Boy Scout knew that you could push a stick into the ground and put a pebble or wooden peg on the tip of the shadow. Wait an hour and put a pebble or wooden peg on the tip of the shadow. The line between the two pebbles is the true east west line.
Close but not quit right. Your line will only run tru E-W if you picked times equidistant on either side of local noon. Cf- if you picked 5 PM & 6 PM, with 6PM being just before sunset on the day oif the equinox, then the shadow would be pointing due east from the pole. At 5 PM on that day, the shadow would be running a little to the north by NE, so the line connecting the end points would run north by NW.

Even right on the equator, the days & nights are only equal on the equinox (Cf- meaning of Tropic of Cancer & Capricorn) although it's true there is only a little variation from day to day, season to season comared to the higher latitiudes. Cf- Land of the Midnight Sun.

Astology may have some basis in truth. There does seem to be changes in animal behavior and plant phenology/physiology based on light (solar) cycles, and human behavior does have some correlation with lunar cycles (possibley due to gravitational effects on fluid/elecrolyte balance in brains.)....Babies born in cold, winter months may be cuddled more and those born in warm months cuddled less wich may certainly affect personilities....Whether or not these phenomena can be genralized and translatred into actionable policy concerning individuals is debatable.
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Old 02-17-2023, 11:07 AM
 
Location: Westwood, MA
5,037 posts, read 6,850,450 times
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Quote:
Originally Posted by guidoLaMoto View Post
Close but not quit right. Your line will only run tru E-W if you picked times equidistant on either side of local noon. Cf- if you picked 5 PM & 6 PM, with 6PM being just before sunset on the day oif the equinox, then the shadow would be pointing due east from the pole. At 5 PM on that day, the shadow would be running a little to the north by NE, so the line connecting the end points would run north by NW.
The trick here is to mark the shadow before noon and then use a line to make an arc centered about the rod and intersecting the first mark. Where the shadow crosses the arc in the afternoon will be on the exact opposite of local noon. Together with the first point this will define true East-west accurately.
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Old 02-17-2023, 11:28 AM
 
Location: Middle America
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Quote:
Originally Posted by CosmicWizard View Post
Actually IT IS ASTROLOGY.
The astrology I know of (though definitely don't practice) is about divination and making predictions based on the position of planets against the background of the sky.

Locating true north is more along the lines of science and astronomy.
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Old 02-17-2023, 03:15 PM
 
8,330 posts, read 7,264,103 times
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Quote:
Originally Posted by guidoLaMoto View Post
Close but not quit right. Your line will only run tru E-W if you picked times equidistant on either side of local noon.
No, the line is almost always true E-W. There are two angles in play here, the elevation of the Sun from the equator, and the azimuth of the Sun from true north. The changes in these two angles as the Sun appears to move across the sky means that the shadow of the tip of the upright stick traces a straight line from west to east. This video, while somewhat tedious, does illustrate the concept. The time point from 6:30 to 7:45 in the video shows the straight line traced out by the changing position of the stick's shadow.


https://www.youtube.com/watch?v=u3l49zQREcY

There are some end-cases where this method might not work, I'm thinking the hour after sunrise and the hour before sunset, when in the northern hemisphere the Sun rises and sets north of the east-west line. That might throw off the method.
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Old 02-18-2023, 08:18 AM
 
Location: Wherabouts Unknown!
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Quote:
Originally Posted by Thoreau424 View Post
The astrology I know of (though definitely don't practice) is about divination and making predictions based on the position of planets against the background of the sky.
That is definitely one component of astrology, but not the whole ball of wax.

Quote:
Locating true north is more along the lines of science and astronomy.
Yes, astrology relies on science and astronomy to generate a basic horoscope.
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Old 02-18-2023, 10:38 AM
 
Location: The Driftless Area, WI
7,102 posts, read 4,915,886 times
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Quote:
Originally Posted by djmilf View Post
No, the line is almost always true E-W. There are two angles in play here, the elevation of the Sun from the equator, and the azimuth of the Sun from true north. The changes in these two angles as the Sun appears to move across the sky means that the shadow of the tip of the upright stick traces a straight line from west to east. This video, while somewhat tedious, does illustrate the concept. The time point from 6:30 to 7:45 in the video shows the straight line traced out by the changing position of the stick's shadow.


https://www.youtube.com/watch?v=u3l49zQREcY

There are some end-cases where this method might not work, I'm thinking the hour after sunrise and the hour before sunset, when in the northern hemisphere the Sun rises and sets north of the east-west line. That might throw off the method.
As the guy says towards the end-- it's very close to true E-W. My example shows where it's way off. The closer to noon your measurements are, the more accurate it its, but the only exact mesaurement is when the two points are taken eually on either side of noon. It's like the secant cord to estimate a tangent line vs a differential.

How accurate do you need to be? If you're resorting to this, then you must be lost and close enough is good enough.
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Old 02-18-2023, 12:38 PM
 
Location: Wherabouts Unknown!
7,841 posts, read 18,907,092 times
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guidoLaMoto & djmilf & jayrandom .... you guys might be interested in an online astrology tool that calculates the Vertex ( west point ) and the Anti-Vertex ( east point ). I've not used it myself so I won't vouch for it's accuracy.

https://horoscopes.astro-seek.com/as...ign-calculator

Vertex and Anti-Vertex
"The Vertex is due west and the opposite point, the Antivertex, is due east." ~Steve Cozzi~

Last edited by CosmicWizard; 02-18-2023 at 01:07 PM..
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Old 02-18-2023, 02:04 PM
 
Location: Westwood, MA
5,037 posts, read 6,850,450 times
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Quote:
Originally Posted by CosmicWizard View Post
guidoLaMoto & djmilf & jayrandom .... you guys might be interested in an online astrology tool that calculates the Vertex ( west point ) and the Anti-Vertex ( east point ). I've not used it myself so I won't vouch for it's accuracy.

https://horoscopes.astro-seek.com/as...ign-calculator

Vertex and Anti-Vertex
"The Vertex is due west and the opposite point, the Antivertex, is due east." ~Steve Cozzi~
I have a German equatorial mount telescope, so I already have a pretty good way of determining absolute direction. I also have a compass and access to the local declination if it’s day time. And my phone if I’m feeling particularly lazy.
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Old 02-18-2023, 02:56 PM
 
Location: Wherabouts Unknown!
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Quote:
Originally Posted by jayrandom View Post
I have a German equatorial mount telescope
That would be nice to have!
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Old 02-20-2023, 11:46 AM
 
8,330 posts, read 7,264,103 times
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Quote:
Originally Posted by CosmicWizard View Post
guidoLaMoto & djmilf & jayrandom .... you guys might be interested in an online astrology tool that calculates the Vertex ( west point ) and the Anti-Vertex ( east point ). I've not used it myself so I won't vouch for it's accuracy.

https://horoscopes.astro-seek.com/as...ign-calculator

Vertex and Anti-Vertex
"The Vertex is due west and the opposite point, the Antivertex, is due east." ~Steve Cozzi~
Don't need it.

I've got my sticks, a level area lit with bright sunlight, and a spare 30 minutes or so.

If I need to find directions quicker, I suppose I could just use the Compass app on my iPhone.

Neither requires astrology.
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