Sundials

History of Sundial

• A sundial is a device that measures time by the position of the sun.

• Used to tell time up until the 1800’s• Archaeological finds discover “shadow clocks”

in 1500 B.C.E. in Egypt.• Used by prominent civilizations through

ancient history to tell time.

How sundials work

• In most designs a sundial consist of two parts; the gnomon and the dial. The gnomon usually a triangle in shape is placed in the middle of the dial facing as close to True North as possible for best accuracy. All dials are constructed differently based on what latitude you are located. This is done by adjusting how close or far the time lines are upon the dial. As the sun rises it will cast a shadow across the gnomon and project it upon the dial the point of this shadow on the dial best describes the time of day.

Assignment

• With your mentors you will construct a sundial and proceed outside and record your findings with in a hour of accuracy.

• These materials will be provided:• construction paper• scissors• drinking straws• glue• cardboard• sunny day• sundial template