A sundial is one of the most common decorative ornaments seen in flower gardens today, providing quiet, aesthetic beauty as it peeks out from the rose bushes and hydrangeas. It’s hard to imagine, but this simple device once served entire civilizations as the only means to tell time.
The earliest design of the sundial dates as far back as 3500 BC, where a simple stick wedged in the earth monitored the shadows of the passing day. And although no one knows for certain who actually invented the sundial, its credit goes mainly to the ancient Egyptians who, by 1500 BC, had perfected the “shadow clock,” a more portable device that measured time throughout the day. But other civilizations, including the ancient Babylonians, Greeks and Mayans, also understood that time could be calculated by the position of the Sun in the sky and the shadows it cast on objects below.
If you go to the beach with the family and pitch your umbrella in the sand, you can get a basic understanding of how sundials work. As you enjoy the afternoon by the ocean, you may notice how the shadow your umbrella casts on the sand changes throughout the day. Without even looking at your watch, you probably know when it’s time to head home by where the Sun is in the sky and the position of your umbrella’s shadow.
Early man’s need to tell time
Every civilization has been fascinated with the way the Sun “moves” across the sky (it was always believed that the Earth was fixed in the center of the heavens and the Sun orbited around it). And while no one can say exactly when early man began using the Sun, Moon and stars in the sky to tell time, it was most certainly born of necessity: He needed to have an accurate understanding of the seasons to know when to plant and harvest crops, and telling time became a matter of basic survival. Of course looking up, certain times of the day were obvious: when the sun rose and when it set, and the time of day when it was at its highest point (Noon), when shadows were shortest. As civilizations developed, it became more and more important to know the time during the day.
To boldly go where gnomon has gone before
The earliest sundial design may have begun with a simple stick in the ground to cast a shadow, but it soon developed into a triangular pointer known as a gnomon (pronounced “no-mon”), which stands in the center of a round dial etched with numbers. The shadow cast by the gnomon moves around the face of the numbered dial as the day progresses, to tell time. As sundials became more common, the gnomon became shorter and eventually pointed to the north, rather than straight up. Different shapes emerged, such as spheres, cylinders and cones, and sizes ranged from tiny pocket dials to giant dials in observatories.
Over time, the sundial became more complex, and also more accurate. Modern astronomers and mathematicians knew they needed to make adjustments, accounting for the Earth’s tilted axis (light from the sun hits the planet differently throughout the year), for the elliptical shape of the Earth’s orbit around the sun, and for the fact that seasons affect the length of shadows (winter shadows are longer than summer shadows). Because of its accuracy, the sundial was actually used to check and adjust the time on mechanical clocks right up until the late 19th century.
So while the sundial is used mostly as a garden decoration today, its place in history is quite significant. In fact, nearly all of the clocks and calendars we use today have strong roots in ancient models, including that of the simple sundial.
Fun Sundial Fact:
Did you know that traditionally, most sundials are engraved with a motto in the form of an epigram? Sometimes these messages appear (often in Latin) as a somber reflection on the passing of time or to remind us that life is short, but many times, the dial maker simply wanted to express his sense of humor and wit. The Latin phrase, Carpe Diem (Seize the Day), is an example of an often-used sundial motto. A lighter motto, etched on a German sundial, reads Mach’ es wie die Sonnenuhr; Zähl’ die heitren Stunden nur! (Do like a sundial; count only the sunny hours!). Good advice!