Sundial Project
« on: March 27, 2019, 02:57:50 AM »
Hello, this is my first post.

I have been many times as a guest and found very interesting stuff, I have briefly read the wiki as well.
I have a project to build a sundial at home but i don't really know how. I thought I would start by building a digital model of the Earth and the sun to see where the light comes from and see if I can make the design instead of measuring the shadows outdoors wich would take a whole year.

I have started by reading the wiki about the diameter of the earth. Acording to Eratostenes, the diameter of the known part of the Earth was 25000 nautical miles. That makes 46300Km. The Ecuator is obviously half of it.
Then I have drawn the path of the sun. The wiki says the last research estimates the sun height at about 3000 miles, 4828Km.

I attach a capture of what I have done so far:

I guess the next step is to figure out what is the diameter of the sun path in winter and summer. do you guys have made any research or know where to find it?


Re: Sundial Project
« Reply #1 on: March 28, 2019, 08:25:58 PM »
I have used the map of Gleason's to find out the diameter of the tropics.

According to Gleason's map, the sun is right on top of the tropics during the solstices.

the result is the following: