Shadow Stick

Interpret simple shadow stick data to determine local noon and observer's longitude

An interesting project is to plot the shadow of the Sun over the course of a day at various times of year.

Every hour place a mark with the time at the end of the shadow of the stick. Plot regularly over the midday period. You may find the shortest shadow does not occur at midday on your watch. The stick is showing apparent solar time.

At the end of the day you will end with an interesting pattern.

Repeat the exercise on another date but this time put another date or use another pencil so you can see the difference between the dates.

See the animation for further instructions.

The point of this that the Sun casts different shadows at the same time of day throughout the year. This happens because of Earth's elliptical orbit and axis.


Links New Window

Sunship 2005 Shadow Stick Experiment

Black Hawk College - Shadow Stick Astronomy Diurnal Motion of the Sun Observed with a Gnomon


What can be found out through observations made with a shadow stick?