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Tracking the Sun starting at solar noon?

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gary350

Well-Known Member
I have a 1" diameter PVC pipe 4 ft long with a solar cell at the bottom. When sun light goes down the pipe a small voltage closes a relay that turns something on.

I used a compass to pull a string between 2 stakes so string is North South.

I have a metal rod in the ground at 45 degree angle with a plum bob to get the metal rod pointer exactly over the string like a sun dial.

At magnet noon shadow of metal rod lines up with the string.

How do I find solar noon at my house????????
 

Inquisitive

Super Moderator
Try entering your local longitude and latitude in google webpage like this.

https://www.google.com/search?q=murfreesboro+tn+longitude+latitude&oq=murfreesboro,+tn+longti&aqs=chrome.1.69i57j0.12425j0j8&sourceid=chrome&ie=UTF-8

Then use the longitude and latitude it gives for the map below at NOAA

Enter your house address in this calculator

https://mynasadata.larc.nasa.gov/latitudelongitude-finder/

Place data in the below link.

https://www.esrl.noaa.gov/gmd/grad/solcalc/

It will give you your solar noon calculation.
 
Last edited:

JimB

Super Moderator
Most Helpful Member
I used a compass to pull a string between 2 stakes so string is North South.
Have you allowed for magnetic variation?

When sun light goes down the pipe a small voltage closes a relay that turns something on.
The elevation of the sun at noon will vary throughout the year.

I have a feeling that this my not be quite as simple as you expect.

JimB
 

alec_t

Well-Known Member
Most Helpful Member
I have a metal rod in the ground at 45 degree angle
If the rod is the gnomon of your 'sundial' then it should be at an angle equal to your latitude, not 45°.
 

gary350

Well-Known Member
Try entering your local longitude and latitude in google webpage like this.

https://www.google.com/search?q=murfreesboro+tn+longitude+latitude&oq=murfreesboro,+tn+longti&aqs=chrome.1.69i57j0.12425j0j8&sourceid=chrome&ie=UTF-8

Then use the longitude and latitude it gives for the map below at NOAA

Enter your house address in this calcultor

https://mynasadata.larc.nasa.gov/latitudelongitude-finder/

Place data in the below link.

https://www.esrl.noaa.gov/gmd/grad/solcalc/

It will give you your solar noon calculation.

My car GPS says ############### <Mod Censored>

I put this GPS into Google Map it shows where I am standing in my driveway so I know it is correct.

I type this information ############### <Mod Censored> into noaa it wants my location so I type in Murfreesboro TN 37129 it show me in a building in Tulsa OK.

So I type in only my zip code 37129 now it shows me in the middle of a lake.

I type on Murfreesboro TN with no zip code it shows me on a sand bar in a river not sure what river that is.

Now I type in Earth and get no reply.

I already found this noaa thing I can not make it work.

If I only knew sun rise + sun set then divide by 2 I will have solar noon.
 
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Inquisitive

Super Moderator
If you enter your GPS coordinates into Google Maps it will display the longitude & latitude right under it.

July 2 solar noon will be 11:49:57 seconds
 

Inquisitive

Super Moderator
I calculate tomorrow

July 3
Apparent Sunrise 04:34
Solar Noon 11:50:08
Apparent Sunset 19:06
 

Inquisitive

Super Moderator
Without giving away your personal address. Let me show you how I came up with the answer.

My address for this example is the Statue of Liberty in New York.

Go to Google.com and enter "statue of liberty gps coordinates" <Enter>

Google returns the below image.
Liberty1.PNG
Next copy the GPS coordinates into Google Maps

Google Maps displays as below.
Liberty.PNG
The bottom set of numbers are the longitude and latitude of Lady Liberty

Now using the lower numbers enter those into the Noaa solar calculator.

https://www.esrl.noaa.gov/gmd/grad/solcalc/

After you enter the Longitude and Latitude in the calculator hit the "tab" key to update the data.

Let me know if that does not work for you.
 

gary350

Well-Known Member
Without giving away your personal address. Let me show you how I came up with the answer.

My address for this example is the Statue of Liberty in New York.

Go to Google.com and enter "statue of liberty gps coordinates" <Enter>

Google returns the below image.
View attachment 113646
Next copy the GPS coordinates into Google Maps

Google Maps displays as below.
View attachment 113647
The bottom set of numbers are the longitude and latitude of Lady Liberty

Now using the lower numbers enter those into the Noaa solar calculator.

https://www.esrl.noaa.gov/gmd/grad/solcalc/

After you enter the Longitude and Latitude in the calculator hit the "tab" key to update the data.

Let me know if that does not work for you.
Every sense my computer forced me to update Google Maps is a problem no matter what I type in it wants to install maps, I click yes it acts like it is doing something the screen goes blank and stays blank for hours unless I close it and start over.

This is what I have from my GPS. 35 52.802 N 086 27.684 W if I type that in it does not work but if I leave off the N & W I get something crazy.

I tried 35 52.802 086 27.684 this does not work either

I tried 35.52802 086. 27684 this tells me solar noon is 7:54 am

I think the numbers I am typing in have the . in the wrong place. I have to leave off N & W and get the numbers right.

After I type in the numbers it wants to know what time zone I am in it show -6 and that seems to be correct.

With DST clicked answer is solar noon = 1:18 55 pm this has to be correct. Last time I checked magnetic noon was 1:12 pm. I knew SN & MN had to be close together I was guessing 20 minutes or so apart.

2 days ago I came up with 22 minutes between SN & MN I set up the string and stake in the yard north south and timed the shadow 22 minutes the angle between the 2 shadows is 6.8 degrees.

Now I know angle between SN & NM is about 6 minutes I need to check it again with the sun in the yard angle should be about 1.85 degrees between the string and shadow.
 
Last edited:

Pommie

Well-Known Member
Most Helpful Member
I would guess the values are degrees minutes and fractions of minutes and google wants degrees and fractions of degrees.

Mike.
Edit, So, 35 52.802 becomes 35.8800333 and 86 27.68 becomes 86.461333
 

atferrari

Well-Known Member
There is a simple concept, to what JimB alluded to: the maximum elevation (angle measured by the observer between horizon and Sun), occurs when the Sun is passing above your meridian. In fact, that was precisely what we do (did) at sea with the sextant.

I would stay away of anything related to magnetic measurements which could easily be affected by ferromagnetics structures nearby. I would try a sundial to pinpoint the moment.
 

gary350

Well-Known Member
I just learned something new. Assume your standing on the sun looking at earth with true north straight up to the north star and magnet north to the right. 6 hrs later earth has rotated 90 degrees and magnet north is pointing straight at the sun. Another 6 hrs later magnetic north is pointing to the left. 6 hrs later magnetic north is pointing away from the sun. Depending on where you live on earth the angle between magnet north and true north will be different at solar noon for you and your geographical location. There are 6 time zones from east Canada to Alaska if magnetic north pointing straight at the sun in Alaska at the exact same time magnet north is point to the right in Canada. But 3 months later as earth rotates around the sun magnet noon is now rotated 90 degrees to the west. If I take a magnet noon reading with a compass and homemade type sun dial rod stuck in the ground at 45 degree angle north the angle between solar noon and magnet noon will never be the same from day to day. I probably will not notice changes from day to day but changes from month to month will be easy to detect. I was hoping to use magnetic noon to find solar noon by checking the angle of the shadow to true north but it is changing every day. 2 times every year solar noon and magnet noon will be at the same time. 3 months later and 9 months later magnet noon will be as far as it gets from solar noon.

I never thought about it until now but if you drive your car from east Canada to Alaska through 6 times zones you have driven 1/4 of the way around earth.
 

gary350

Well-Known Member
I finally found the information I need to know. Solar noon is 4 degrees before magnetic noon. Solar noon is 356 degrees magnetic.
 
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