2025/11/16

Sundial

A sundial is a device that measures local time during the day by using the position of the sun in the sky. The most common type of sundial consists of a rod (gnomon) placed on a flat surface, with the hours of the day marked on the surface. As the sun’s position in the sky changes, the shadow cast by the rod moves across the surface, indicating the time.

Various types of sundials have been designed, all of which operate based on the sun’s position in the sky and the length of the shadow. One indicator is the object that casts a shadow on the dial. Sundials are generally divided into two main categories: those that use a point or line of light to indicate time, and those that use a shadow-casting blade. In both cases, the light or shadow falls on a surface marked with lines and symbols representing the hours.

The most important models of sundials include horizontal, vertical, equatorial, polar, ring, analemmatic, composite, and digital sundials. In each type, the light or shadow falls on a surface where the hours are represented by lines and symbols.

At the Earth Physics Park, part of the Earth Science Park Museum in Mashhad, the sundial section includes five sundial models, one of which is an analemmatic sundial. In this type, the visitor themselves acts as the indicator, using their own shadow to tell the time. Next to this life-sized sundial, four smaller sundials are displayed, each representing a specific type of sundial.

The sundials in this museum park were designed and installed by Engareh Physics Toos Company in 2017 (1396 in the Iranian calendar).