The Math involved.

[leee (Thomas)]

I drug out an old Tractor Disk. Thinking to make a Sundial on it.
So I go to the Web. Looking for the math, to set up the Hour lines, the Gnomon. How to adjust for the Seasons. Etc.
I need to go back to School. The Math involved !!!

[xelasnave]

Hi Thomas, may I take the opportunity to wish you and your family a Merry Christmas.

It can't be hard...but an exciting approach would be to mark the spots each day over the years...I expect that is how they built the first Sun dials.

First get your "hour" lines in place ..that is easy.

I had an idea to weld many pipes together so at Noon the light would illuminate a clear plastic plug in one pipe ...but then I saw a watch in Kmart for $10 and I thought that is probably going to be cheaper...so I bought the watch...clearly you are feeling creative and artistic and that is a wonderful thing.
Alex

Good luck.
Alex

[redbeard (Damien)]

Could you buy a cheap plastic sundial and simply copy/transfer the 'lines' across to the one you build. Homework has been done and no math required.


Cheers,
Damien.

[julianh72 (Julian)]

You could try an equatorial sundial, rather than the more common horizontal sundial. They are MUCH easier to set-up, but can suffer from the disadvantage that depending on latitude and season, the gnomon’s shadow can fall on either the top or bottom of the disk. If you mark your disk on both faces, and weld a rod as the gnomon through the disk, you can read the time on the underside when necessary.

https://skyandtelescope.org/observin...ake-a-sundial/

Personally, I like the idea of a digital sundial!
https://www.thingiverse.com/thing:1068443

[PCH (Paul)]

Just thinking about this and the difficulties involved, gives you an appreciation of just how clever the people of old were hey!

[xelasnave]

Here is a brief article for those who may be interested that again shows why why owe most everything to the Sumerians...I can never fathom why they are not the first thing you would learn in modern history rather than say the Eygiptians...https://www.ancient.eu/article/71/su...ng-the-future/
Alex

[leee (Thomas)]

I thought - for a moment - the math involved in making a Sundial would be 'fun'' Challenging. https://files.eric.ed.gov/fulltext/EJ802706.pdf

I am going with a Template.
AH - if there was but a Template - for Marriage for example. A nice 'Cut & Paste'
Like my Sundial is going to be.

[rrussell1962]

Patrick Moore's Astronomy for O Level book had an easy to follow plan for making a sundial which I used to chart the equation of time when I did the O Level many years ago. They should be online somewhere.

[mura_gadi (Steve)]

Hello,

You can also tell the time via the southern cross at night. Well worth a search if you can remember a few basic +/- functions which are month dependent.

From memory a New Zealand astronomy club had the easiest write-up of how to do it. And kinda fun to tell the kids about.


Merry Christmas all
Steve
Ps. link below
https://oneminuteastronomer.com/3322...outhern-cross/

Pps. Ok, so more for IceinSpace ppl in the southern hemisphere... but still nice to work with... aka Crocodile Dundee at night...

[leee (Thomas)]

Ah - The things the Sky can tell us.