How to Tell Time with a Sundial

Sundials are the oldest man made timepiece, and telling time with a sundial is very easy. Sundials are not nearly as accurate at telling the time as a clock or watch, but they can give a good estimate of the current time. The shadow of the sun across the face of the sundial moves as the Earth rotates, making a sundial a natural clock.

Difficulty: Easy

Instructions

1. Start telling time with a sundial by learning how the sundial works. The accuracy of the sundial is affected by its proper placement. To be accurate, a sundial must be placed at the proper angle which is dependent upon the latitude of the sundial's location (See Resource below).

2. Study the gnomon. The gnomon is the part of the sundial in the center. The sun's shadow is like the hand on a clock and the gnomon is the center.

3. Check the outer ring of the sundial. There should be a series of numbers around the outer edge. These are often written in Roman Numerals to indicate the ancient nature of the sundial. See where the sun's shadow falls across the face of the sundial.

4. Read the time on the sundial. If a sundial is placed properly it can be accurate to within fifteen minutes. The local time should also account for the seasonal variation of Daylight Savings Time.

5. Enjoy building a sundial. Sundials are a very natural way to learn about time. Making a sundial is a great family activity. Be sure to angle the sundial to the North to align it properly with the sun. Slant the sundial at the proper angle to get an accurate reading.