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Sundial - Sun's Timekeeper: Unraveling the Solar Secrets!

Get ready to unlock the mysteries of timekeeping using the sun's power! We will build a Sundial model. This ancient timekeeping device will help us understand the Earth's rotation, the sun's apparent motion, and the science behind telling time with shadows. With three different methods to orient the sundial accurately, you'll witness the magic of the sun's dance across the sky, guiding the shadow and revealing time like a mystical pointer. 

Develop these Key Competencies:

  • Critical Thinking: Analyze the relationship between the Earth's rotation, the sun's motion, and shadow movement on the sundial.
  • Systems Thinking: Explore the interconnections between timekeeping, solar energy, and ancient timekeepers' ingenuity.


Materials needed

  • Printed or copied Diptych Sundial model on paper
  • Optional: Cardboard for pasting the model
  • Scissors
  • String
  • Compass or magnetic compass
  • Hand watch
  • Safety equipment (gloves, if required)
  • Sunscreen (for outdoor activity)
Activity Description

Step 1: Safety First

  • Before we begin, let's prioritise safety. Put on any necessary safety equipment, such as gloves, and apply sunscreen for outdoor activities.

Step 2: Prepare the Diptych Sundial

  • Print or copy the Diptych Sundial model on paper. For sturdiness, consider pasting it on cardboard.
  • Carefully cut along the outer and dashed lines, following the instructions to create the sundial's shape.

Step 3: Find Your Latitude

  • To customise the sundial to your location, find your latitude using an Atlas or online resources.
  • Mark a line on the sundial's base (marked with 35º-55º scales) that corresponds to your latitude.
  • Draw a line from your latitude through the X symbols at the top of the scale and cut along those lines.
  • Don't forget to note your location/latitude at the top of the sundial.

Step 4: Fold and Mark the Direction

  • Follow the instructions to fold the dotted lines and mark the opposite side for creases.
  • Mark along the horizontal line in the middle (between noon and AM-PM) on the backside and fold to the front. The fins will help you approximate the right angle.

Step 5: Attach the String

  • Create small holes where all the lines meet at the top and bottom of the sundial.
  • Tie a string through those holes. The shadow cast by the string will act as the sundial's pointer and tell the time.

Step 6: Positioning the Sundial

  • For the sundial to function accurately, position it where the pointer (the string) casts a shadow.
  • The sundial must face the North-South direction during the day. This portability allows you to carry it around and experiment with different locations.


Exploring the Science Behind:

  • As we observe the Earth's rotation, we'll discover how it creates the day and night cycle. We'll explore the sun's apparent motion across the sky and understand how it influences the sundial's shadow movement, enabling accurate timekeeping.
  • Learn about the Earth's rotation on its axis, which causes day and night cycles. The sun's apparent motion in the sky leads to the sundial's shadow movement, allowing us to tell time.
  • Understand that a sundial works based on the shadow of a rod, and a simple stick on the ground would not provide accurate timekeeping due to the Earth's axial tilt, causing daily changes in the sun's visible motion.


Did You Know

Sundials were one of the earliest timekeeping devices used by humans, dating back around 4 thousand years ago in Egypt. In the southern hemisphere sundials are inverted and point south!


Safety Note

Remember to use caution when handling sharp objects or tools. Don't forget to apply sunscreen for outdoor activities



Instructional Guide: How to Orient Your Sundial for Accurate Timekeeping

Step 1: Placing the Sundial

  • To ensure your sundial functions accurately, it must be positioned in the right direction, where the pointer (also known as the winding) casts a shadow. The ideal placement is in the North-South direction during the day, allowing you to carry it around for exploration.


Step 2: Three Methods to Orient Your Sundial

Method 1: Correct Method (For Northern Hemisphere)

  • At night, locate the pole star, also known as the north star, in the sky. This star marks the direction of the North.
  • To orient your sundial, position the hand or winding of the sundial within 1º of the north celestial pole, which aligns with the pole star.
  • If you find the pole star at the end of the Ursa Minor constellation, point the hand of your sundial towards the pole star for accurate orientation.
  • For future reference, mark a slight reference point on a window to preserve the device's orientation.
  • Please note that this method is not applicable in the southern hemisphere since no star can help us perform this exercise.

Method 2: Practical Method (Using a Magnetic Compass)

  • A magnetic compass can help determine the north/south line for orientation.
  • However, be aware that there might be a difference between magnetic north and true north. Depending on your location, this difference can result in an hour or more reading variation.
  • Use this method cautiously, especially in regions with significant differences between magnetic north and true north, such as southern latitudes.

Method 3: Easy Method (Using a Hand Watch)

  • As a simple approximation, you can use a hand watch at any time to find the orientation.
  • Position the sundial so that the shadow of the rubber band shows the correct time on the watch.
  • Remember that leaving the sundial in this position can lead to an error of up to 30 minutes throughout the year due to the equation of time.
  • The equation of time accounts for the variations in the Earth's orbit around the sun, resulting in differences of approximately +/- 16 minutes per day from the standard 24-hour day.
  • Orienting the sundial on April 15, June 10, September 1, or December 20 will result in an insignificant error. However, orientations between April 15 and September 1 will have an error of a few minutes due to daylight saving time changes.



Reflect on the activity and determine in which cardinal direction (north, south, east, west) the arrow on the sundial should point to indicate the correct time. Consider the information from the three methods and reflect on the direction (north, south, east, west) in which the arrow on the sundial should point for accurate time indication.


Relevant information if you are facilitating

This captivating activity immerses participants in the science of timekeeping through the sun's power. Encourage critical thinking as they explore different orientation methods and witness the dynamic relationship between the Earth and the sun. The Diptych Sundial serves as a fascinating time capsule, bridging ancient timekeepers with modern-day wonder. Inspire their curious minds to embrace systems thinking and marvel at the celestial dance of time. 

The sundial model is a fantastic tool for timekeeping and understanding the sun's motion. However, please remember that its accuracy may be influenced by factors like geographic location and time of year. Enjoy the exploration and the fascinating world of ancient timekeepers!

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