Jantar Mantar, Jaipur: The Astronomical UNESCO World Heritage Site of India

Jantar Mantar is an astronomical marvel of India that consists of various observatories and instruments related to space. Around 5 observatories were constructed by Maharajah Sawaii Jai Singh II who is also known as the founder of Jaipur. These observatories were designed for the observation of astronomical positions with the naked eye and they embody several architectural and instrumental innovations. 

History

Jai Singh’s Chief Astronomer Jagannatha introduced him to the subject of astronomy and gradually he started gaining interest in it. The ruler read and learned about this subject from many people and got fascinated with it. When Jai Singh got acquainted with astronomy, he learnt about the astrolabe, an ancient instrument that can be used to map the local sky and make a variety of astronomical calculations. This instrument was used by researchers and scientists but Jai Singh noted that the tables that had been created earlier were often not in agreement with current observations. To address this, he envisioned an observatory with the stability and permanence of masonry, combined with the precision achievable through large-scale structures. This vision led to the creation of Jantar Mantar.

Present Day 

In today’s time, Jantar Mantar is one of the most significant, comprehensive, and best-preserved historic observatories of India. The observatory forms part of a tradition of Ptolemaic positional astronomy which was shared by many civilisations. It contributes this type of observation to the completion of the astronomical tables of Zij -  an Islamic astronomical book that tabulates parameters used for astronomical calculations of the positions of the sun, moon, stars, and planets. 

Housing a set of some 20 main fixed instruments, this place is an epitome of naked-eye astronomical observations. Instruments in many cases have specific characteristics of their own and some of them being the largest open structures. 

Vrihat Samrat 

The Vrihat Samrat Yantra, sometimes called “Supreme Instrument” is probably the largest gnomon-sundial ever built. This yantra (instrument) measures time to a precession, most of the time to an accuracy of two seconds.  

Sasthamsa 

On both sides of the Vrihat Samrat Yantra are Sasthamsa Yantras. Sasthamsa which means “sextant” is an instrument for measuring angular distances used especially in navigation to observe altitudes of celestial bodies. 

Digamasa 

The Digamsa Yantra consists of two concentric cylindrical walls surrounding a central pillar. The top surfaces of the inner and outer walls are marked in angular divisions as fine as 1/10th of a degree and are used to determine the azimuth of a celestial object. 

Ram Yantra 

Rama Yantra is an instrument that has a pair of cylindrical structures, open to the sky, each with a pillar or pole at the centre of the same height. This device is used to observe the position of any celestial object by aligning an object in the sky. In the daytime, the sun’s position is directly observed at the point where the shadow of the top of the pillar falls on the floor or wall. At night, an observer aligns the star or planet with the top of the pillar and interpolates the point on the floor or wall that completes the alignment through the use of a sighting guide.

Nadivalaya 

The Nadivalaya consists of two circular surfaces that are parallel to the equatorial plane and have metal rods positioned at their centres that point in the direction of the poles. This device is an excellent indicator of the equinoxes. 

Rasivalaya 

Rasivalaya is a unique group of 12 gnomon-dials to measure the ecliptic coordinates of celestial objects, each becoming operative when a different one of the 12 zodiacal constellations straddles the meridian.

Daksinottara Bhitti

The Daksinottara Bhitti is based on the meridian dial of earlier times. This device is used to measure astronomical data such as local latitude and the obliquity of the ecliptic. At midday, the sun casts a shadow of the rod onto the quadrant scale, giving the meridian altitude. The instrument may also be used at night to obtain the meridian altitude of other celestial bodies.

Jai Prakash

Jai Prakash is a highly innovative sundial made of two hemispherical bowls that produce an inverse image of the sky and allow the observer to move freely around inside to take readings.

Kapala 

Kapala is another instrument that can record the co-ordinates of celestial bodies in both the azimuth-altitude and equatorial systems, and permits a direct visual transformation of the co-ordinates of any point in the sky between the two systems;

These are some yantras, out of many at Jantar Mantar that grab the attention of architects, artists, and art historians around the world with their striking combinations of geometric forms on a large scale.