Sun Position for a Precise Moment

Have you ever wondered how ancient cultures aligned their buildings with the path of the sun, like Stonehenge with the solstices?

I wanted to do something similar but with a specific moment down to the minute! Due to the Earth's symmetry, this moment occurs twice a year.

For this project, I used:

-Laser cutter

-MDF board

-Sunny day

It is also necessary to know the exact geographical north. To find it, I followed this instructable. Additionally, a level surface is required.

Find the north at the location where you want to place the box and ensure that your surface is level. Then, use a website like https://www.suncalc.org to find the azimuth and altitude for the specific moment and location you need.

You can use a website like https://www.makercase.com/#/basicbox to design a simple box. I made mine out of 3mm MDF with finger joints. I used AutoCAD to modify the DXF file, copying one side of the box to create an inner wall. And also cut down openings for the finger joints.

Using the altitude of the sun at the desired moment, draw the corresponding angle on the side of the box. Then, determine at which height in which layer the path of sunlight will align. Be careful to take into consideration the thickness of the material

Using the Azimuth of the sun at the desired moment, draw the corresponding angle on the base of the box. Then, determine at which height in which layer the path of sunlight will align. Be careful to take into consideration the thickness of the material.

Using both the altitude and azimuth cut down the area on each layer of the box where they intersect. This is the opportunity to create an interesting design that becomes clear at a specific moment of the day, an idea could be to have different parts of the design on different layers. For this proof of concept, I just made a square, but I plan to try more complicated designs in the future.

I offset some of the finger joints to prevent any possibility of assembling the box incorrectly. Place the box at the desired location, taking north into account. In my design, one side of the box aligns with the reference point I used to measure north (my window).

During the testing of a prototype, it was quite a cloudy day, and the light was diffused and the result was as shown in the picture, unclear. To address this, using smaller holes or more layers could ensure that only light at a specific angle reaches the bottom of the box. Ideally, on a sunny day, all the rays of the sun will be perpendicular.