Imagine you have a stick

Imagine you have a stick, approximately your own lenght.

You are standing in an open clearing that has sunlight through out the day.
Put the stick in the ground, stand it up straight.

Congratulations, you have just made a calender. All you need to do now is program it.

Every day, when the sun is at its highest point of that day, place a pebble at the tip of the shadow thrown by your stick. If you keep doing this daily you will end up with a pattern that is an imprint of the sun’s movement in the sky.

You may expect to see a straight line going up and down, but you will not. Instead, you will see an analemma (a figure-8 pattern).

As you may know, the earth spins on a tilted axis, around the sun. This causes all kinds of fluctuations (that I will not get into here), that are responsible for the perceived pattern 8 wobble in the sun’s daily highest position over time.

once you have laid down 365 pebbles, you’re calender is ready for use. From now on, simply track the shadow over the stones to know how far you are from mid-winter or midsummer.