Why is time called "time"

In ancient times, people used "sundials" to measure time. A sundial is an instrument for measuring time, which is used to observe the shadow of the sun to determine the time. It usually consists of a copper pointer and a stone disk. The pointer made of copper is called "needle", which passes through the center of the disk vertically, and the disk made of stone is called "face".

When the sun shines on the sundial, the shadow of the sundial needle will be projected on the surface of the sundial. The sun will move from east to west in a day, and the shadow projected by the sundial needle on the surface will slowly move from east to west, so as to know the change of time. After long-term observation, the ancients not only learned that the shadow of an object was the shortest at noon in a day, but also found that the shadow was the shortest at noon in summer solstice and the longest at noon in winter solstice. So the length of the shadow at noon is used to determine the solar terms and the length of the year. For example, the longest shadow of an object is measured twice in succession.