Make your own sundial

For a very long time, people have told the time using sundials. They show the time by the position of a shadow.

Image: Your sundial, very similar to this one, should look like this! 

There are many different types of sundials. In this activity you will learn to make a simple sundial, called a horizontal sundial, that can be used to show the time.

What you will need to get started:

• Glue
• A computer printer
• Scissors
• Two pieces of cardboard (one about 30 cm on each side and the other about 15 cm on each side) 

 

Making your sundial

There will be two parts to your sundial, the larger part is the horizontal base, onto which hours are marked. The smaller one is the vertical, triangular part, called a gnomon, which is used to cast a shadow.

The positions of the hour (and half hour) lines on the supplied base on the page after next are correct for Launceston, Tasmania, but the sundial could be used in other parts of Tasmania and still work fairly well. 

1. Print out the base and gnomon on sheets of A4 paper.
2. Cut out the square base and the triangular gnomon (including the rectangular part at the bottom of the triangle).
3. Cut pieces of cardboard to exactly match the shapes of the base and gnomon, and glue the paper shapes to the pieces of cardboard.
4. Cut a slot about 1mm wide in the base. The green line on the base shows where to cut.
5. Insert the gnomon into the base (through the slot), taking note of the north direction marker on the gnomon, which needs to point toward the north edge of the base. The gnomon must be upright.

The bottom of the gnomon will poke through the base, but you may like to add some supports at each corner of the base to raise it, or cut off some of the protruding part. To hold the gnomon upright, it may help to glue two small pieces of cardboard on the base, next to the gnomon, to stop it leaning over.

To use your sundial, make sure that the 12 o’clock line points exactly south. You can find south from your house by using a map − perhaps a map that you can find on the internet. Or you can start by placing the sundial so that it reads correctly, then watch the time change!

Download the full activity sheet