The Human Sundial

What is a sundial and how does it work?

  • A sundial is a device used to measure time by the position of the Sun.

 • The Sun casts a shadow from a thin rod or sharp, straight edge which is called a gnomon (noh-mon), an ancient Greek word meaning “indicator” or “that which reveals”.

 • The shadow falls onto a flat surfaced marked with lines indicating the hours of the day. As the sun moves across the sky, the shadow moves across the hour-lines, indicating time.

What is a human sundial and how does it work?

 • Just as its name implies, a human sundial involves a person acting as the gnomon. The person’s shadow falls on the hour markers, showing the time.

 • The human sundial consists of two parts: a time tally marked with the numbers on titles of time, and a month bar marked with the months. 

 

Time Tally                               Month Bar

• To use the sundial, stand at the very center of the current month marker, facing north and the building.

 • Your shadow falls on the time tally. The inner circle of numbers indicates Daylight Savings Time (April through October). The outer circle designates Standard Time.

The Human Sundial (PDF version)