Make your own sundial
Learn to find the time of the day without the help of a clock!
Theory & Background
Have you ever wondered about this fascinating scientific process? Sundials were used to tell the time of the day in olden times and is based on the principle that the position of the sun changes continuously during the day. In reality, it is the Earth that rotates around the sun making it seem like the sun rises in the east and sets in the west. As the sun moves across the sky, the central post on the sundial casts a shadow on its circular plate. It is just like reading a clock – the marks or calibrations on the plate tell you what time it is.
Required Materials
- Large paper or Styrofoam drinking cup with a plastic lid and straw
- Compass
- Wristwatch
- Permanent marker
- Pencil
- Tape
- Enough small pebbles to fill half of the cup
Estimated Time
15 minutes to set up the instrument and a day to get it working.
Step-By-Step Procedure
Using the pencil, poke a hole on the side of the paper / Styrofoam cup approximately 2 inches below its top (rim).
Place the pebbles in the cup so to give it some weight and hold it upright.
Cover the cup with the plastic lid.
Put the straw through the hole on the side of the cup and its lid while letting about half an inch of the straw stick out from the side.
Secure the straw to the cup by taping it down on the side.
Experiment Tips
- Remember, you can always continue with the marking process in case it becomes cloudy or if you have to leave.
Observation
Simple articles can be used to set up the ancient instrument that was used to tell the time of the day.
Result & Conclusion
Using the wrist watch to calibrate (mark) your home-made sundial, you can use it to tell the time. All that needs to be kept in mind is that it is aligned properly with the straw on the cup’s lid pointing towards the North.