For thousands of years, people have used sundials to measure the passage of time by watching the Sun’s apparent movement across the sky. In fact, the earliest device for telling time was likely the gnomon – a simple upright stick dating back to around 3500 BCE. By looking at the length and direction of its shadow, people could figure out the time of day. Sundials remained the primary tool for telling time right up until the early 19th century, and when carefully placed, they can be accurate down to the minute!
In this activity you will assemble your own simple sundial and see how shadows reveal the hidden clock of the sky.