Jantar Mantar

Jantar Mantar is an observatory built in the 18th century and has a collection of about 19 architectural astronomical instruments. It is very surprising to know that these astronomical instruments are built with cement and marble structures. They can be used to see the time of the day, the zodiac sign of the day, instruments to find the position of heavenly bodies and so on. Jantar Mantar in Jaipur in one of the five observatories that was built by Maharaja Sawai Jai Singh II of Jaipur, and is the largest of the five. The other four are located at New Delhi, Jaipur, Ujjain, Mathura and Varanasi/Banaras.

Jantar Mantar, Jaipur

Sun dial: tells the time with an accuracy of 20 seconds!! Time is 11:42 AM

Jantar Mantar has two sun dials called Smarat Yantra. The first one was a smaller dial that was built as an experiment. The accuracy of this dial was 20 seconds. If you hire a guide, he will tell you how to calculate the time by looking at the shadow that falls on the dial! The sun dial itself is in two sections. The first section is for AM and the other section is for PM. If you visit the place around 12 noon, you can see how the shadow shifts from one section to the other! It is truly a treat to watch and realize such an instrument was built in the era where there was no such modern technology. After the first sun dial was built and tested successfully, a larger sun dial was built and it provides an accuracy of 2 seconds!

Jantar Mantar, Jaipur

Smaller sun dial: Left side for AM and Right side for PM

Jantar Mantar, Jaipur

Bigger sun dial: Tells the time with an accuracy of 2 seconds!

Jai Prakash Yantra is an instrument that measures the rotation of the sun.  It consists of two hemispherical cavities set in the ground that complement each other: that is, if put together they would form one complete hemisphere. Wires are tied north to south and east to west, and at the center, is a small circular iron plate with a hole in the center. The shadow cast by this ring falls on the marble hemisphere below, indicating the sun’s longitude and latitude and the sign of the zodiac through which it is passing.

Jantar Mantar, Jaipur

Jai Prakash Yantra

Jantar Mantar, Jaipur

Full Jai Prakash Yantra: which was used as a test device before coming up with the two-fold device with openings

The Nadi Valaya has two circular plates, facing north and south which are its dials. The wall of the plates is inclined towards the south at such an angle that the instrument remains parallel to the plane of the Earths equator.

Jantar Mantar, Jaipur

Nadi Valaya Uttar Gol

Yantra Raj is another instrument that is used to measure the altitude and position of the heavenly bodies. The instrument can also be used to measure time from the position of certain stars at night. During day time, the time can be measured from the position of the sun!

Jantar Mantar, Jaipur

Yantra Raj

There are many more devices that are present in Jantar Mantar. It is a delight to know how various things can be measured by looking at the position of certain celestial objects while in today’s world, we use so many technologies to achieve the same. If you are visiting Jantar Mantar, I suggest you hire a guide who will explain the devices in detail. Without a guide, you will not be able to understand the importance and significance of the devices, and you may be disappointed by looking at “just” a few structures and may wonder why the place is so popular 🙂



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Where to stay?

  • Jaipur

Distance Chart

From Distance (in km)
Delhi 275
Jodhpur 340
Chandigarh 530

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