Konark Sun Temple in Orissa is an architectural marvel of ancient India. This UNESCO World Heritage Site is a genius work of great architects and astronomers.
The speciality of the temple are intelligently carved 24 Sundials that can be used to tell accurate time of the day with the shadows. Analogous to a modern watch with hour, minutes and seconds hand, the Sundials have 8 major spokes, 8 minor spokes, 240 small beads which can accurately tell time to a minute.
The 8 major spokes divide the 24 hours into 3 hours each. The minor spokes between two major spokes divide the 3 hours into 90 minutes each. The 30 small beads situated on the arc between a major and a minor spoke, divide the 90 minutes into 3 minutes each. The vertical spoke stands for 12 AM, adding 3 hours (3 AM, 6 AM, and so on..) with each spoke.
It shows time in the anticlockwise fashion as the Sun moves from East to West, when you place a pointed object on the centre of the wheel. Depending on the alignment of the shadow on the bead (left, right, centre), you can divide it down to 1 minute. That’s how you can tell the exact time of the day.