Botanical Broadcast: Sundial

Botanical Broadcast: Sundial


The Earth is in constant rotation around the sun, and also in rotation on its axis. Because of this, we can use the sun’s movement patterns to tell us what time it is!

Sundials are the oldest known devices that are used to measure time. They are most commonly made out of stone, clay, or wood, but you can use nearly anything tall and slender as the pillar, or gnomon, of a sundial!

What you need:

  1. Rocks
  2. Playdough or clay
  3. A pencil or long stick
  4. Chalk or markers
  5. A wide flat surface

Step 1

Stick your pencil or stick into the clay so that it points straight up.

Step 2

Write consecutive times of the day with chalk or markers on your rocks. (10am, 11am, 12am, etc).

Step 3

Put your pencil-in-clay on a flat surface, like a paved driveway or a piece of cardboard on your lawn. Make sure it isn’t blocked by anything that could make a shadow and is in full view of the sun.

Step 4

Check your sundial at each time of day you have marked, and place a rock where the shadow falls. By the end of the day, you should have placed all your rocks.

(If you are using a paved driveway and chalk, you can mark times right on the ground and don’t have to use rocks!)

Step 5

Check on it tomorrow and see if your sundial can accurately inform you of the time!