The First Clock - Origin of the Sundial
A sundial is a timepiece that tells the time using the movement of Earth on its axis. As Earth rotates throughout the day, the sun creates shadows that move along with the sun's apparent position in the sky. People discovered that these shadows can be used to tell the time. Although today, it's much more common to glance at a clock or a watch to keep track of the time, people used to rely on the sun to mark the hours.
