A sundial is an instrument that measures time by the position of the sun. Called “rigui” in Chinese, a sundial is a timepiece that indicates the daylight hours by the shadow that the gnomon casts on a calibrated dial in ancient China. A typical sundial is made up of a bronze pointer and a stone dial.

The earliest sundial in the world was created some 6,000 years ago in ancient Babylon. And the earliest sundial of China, according to historical documents, was the flat horizontal dial plate, or the horizontal sundial invented in 574 AD.