Situated within the old city of Jaipur near the City Palace and Hawa Mahal is the UNESCO World Heritage site of Jantar Mantar. Named after the words yantra, which in Sanskrit means “instrument,” and mantrana, meaning “to calculate,” Jantar Mantar is an equinoctial sundial engineered to measure local time and track the declination of the sun alongside the wider celestial sphere.
Sun Dialing the Skies at Jantar Mantar in Jaipur
There were five Jantar Mantar observatories built across India during the early eighteenth century—four of which remain to this day—with the site in Jaipur housing the world's largest stone sundial. A total of nineteen architectural astronomical instruments were placed inside the Jantar Mantar complex in Jaipur during its construction from 1728 to 1738 under the reign of Rajput Maharaja Sawai Jai Singh II.
When the main observatory for tracking heavenly bodies was transferred from Delhi to Jaipur, the number of astronomers working at this site peaked at twenty-three. It continued to serve as the Rajput kingdom's main observatory until the death of Maharaja Sawai Jai Singh II in 1743.
Among the four surviving Jantar Mantar observatories located in Jaipur, Delhi, Varanasi, and Ujjain, this site is considered the most prominent because it features the greatest number of instruments and the world’s largest sundial.
Each of the structural planetary instruments measures celestial positions using the method of Ptolemaic positional astronomy, which was utilized by many ancient civilizations. These instruments supplied accurate readings before towering modern buildings blocked the view of the night sky.
Vrihat Samrat Yantra: The World's Biggest Sundial
Occupying the central space of Jantar Mantar is a massive sundial with a gigantic gnomon standing ninety feet high. The gnomon is the part of a sundial that measures the sun's position through the shadow it casts.
The Vrihat Samrat Yantra measures time in intervals of two seconds using the shadow cast by the gnomon under the sunlight.
Walking through the Jantar Mantar complex in Jaipur is like exploring an open-air museum of architectural astronomy. In this sanctuary, each apparatus takes on a unique structural form with intricate patterns and designs precisely engineered to track the movements of celestial bodies.
Among the architectural planetary instruments that captured my attention the most was the Laghu Samrat Yantra, which appears to be a staircase but is actually a geometric ramp pointed toward the North Pole, used to calculate local time down to an accuracy of twenty seconds.
There is also the Ram Yantra, a structure resembling a giant wheel positioned on the ground and surrounded by pillars in a circular formation, designed to measure the azimuth and elevation of the sun and planets.
The Nadivalaya Yantra consists of a structure featuring dual sundials facing the northern and southern hemispheres, capable of measuring time to an accuracy of less than one minute.
Another extraordinary instrument is the Jaya Prakash Yantra, which consists of hollowed hemispherical marble bowls embedded in the ground to track the hourly coordinates of heavenly bodies.
Each of these instruments provides a profound look into the brilliance of early Indian astronomers who, despite lacking modern equipment, developed highly precise, thought-provoking methods to study and measure celestial bodies across the sky.
