Skip to main content

Jantar Mantar - a marvellous astronomical observatory

India tourism is filled with many incredible monuments that have stood the test of time and constantly been a source of study as well as inspiration for historians, sculptors, and scientists alike. A cradle of civilization, India has offered a lot to the modern word. The country’s glorious past has produced many marvellous forms of arts, architecture, music, and literature. One of the most visited countries in the world, this multicultural nation has always attracted visitors from the Western world who love exploring its diverse landscape and stunning masterpieces. One such stellar structure is the Jantar Manar, an equinoctial sundial often considered to be one of the largest observatories ever built on earth. The word ‘jantra’ is derived from ‘yantra’ meaning instrument, while the suffix Mantar is derived from ‘mantrana’ meaning consult or calculate.

Jantar Mantar was the name given to a series of five structures built in Jaipur, New Delhi, Ujjain, Varanasi and Mathura, of which the largest is in the Pink City featuring many instruments along with the world’s largest stone sundial. These magnificent structures were designed by combining concepts of religion, science, and art. The Jantars have suggestive names like Samrat Yantra, Jai Prakash, Ram Yantra and Niyati Chakra; each of which is used to for various astronomical calculations. The primary purpose of the observatory was to compile astronomical tables and to predict the times and movements of the sun, moon, and planets thus allowing the observation of astronomical positions with the naked eye. Jantar Mantar is truly a unique offering of a Jaipur city tour.  

The Jantar Mantar in Jaipur is a collection of nineteen such instruments. The capital city of Rajasthan was the seat of Maharaja Jai Singh II who oversaw the completion of this monument in the year 1734. A renowned scholar and a passionate astrologer, the Maharaja studied philosophy, astrology, architecture, and religion and was also well versed with universal mathematical concepts as well. The Jaipur observatory was functional for seven years only, as the Maharaja was not very successful in deriving accurate, astronomical observations.

Located near City Palace and Hawa Mahal, the one in Jaipur features masonry, stone and brass instruments that were built using astronomy and instrument design principles of ancient Sanskrit texts. The monument showcases architectural innovations as well as an amalgamation of ideas from different religious and social beliefs of that era. The observatory is an example of the Ptolemaic positional astronomy which was shared by many civilizations. It has been renovated many times and houses various instruments offering precise measurements of time, the azimuth, and declination of the sun. It also offers the positions of constellations, along with several other astronomical phenomena.

The nineteen instruments in the Jaipur observatory are:

  •    Chakra Yantra (four semicircular arcs on which a gnomon casts a shadow, thereby giving the declination of the Sun at four specified times of the day)
  •    Dakshin Bhitti Yantra (measures meridian, altitude and zenith distances of celestial bodies)[9]
  •    Digamsha Yantra (a pillar in the middle of two concentric outer circles, used to measure azimuth of the sun, and to calculate the time of sunrise and sunset forecasts)[10]
  •    Disha Yantra
  •    Dhruva Darshak Pattika (observe and find the location of pole star with respect to other celestial bodies)[10]
  •    Jai Prakash Yantra (two hemispherical bowl-based sundials with marked marble slabs that map inverted image of sky and allows the observer to move inside the instrument, measures altitudes, azimuths, hour angles and declinations)[3][9]
  •    Kapali Yantra (measures coordinates of celestial bodies in azimuth and equatorial systems, any point in sky can be visually transformed from one coordinate system to another)[6]
  •    Kanali Yantra
  •    Kranti Vritta Yantra (measures longitude and latitude of celestial bodies)
  •    Laghu Samrat Yantra (the smaller sundial at the monument, inclined at 27 degrees, to measure time, less accurate than Vrihat Samrat Yantra)[10]
  •    Misra Yantra
  •    Nadi Valaya Yantra (two sundials on different faces of the instrument, the two faces represent north and south hemispheres, the accuracy of the instrument in measuring the time is less than a minute)[10]
  •    Palbha Yantra
  •    Rama Yantra (a double cylinder instrument that measures azimuth and altitudes of celestial bodies)[9]
  •    Rashi Valaya Yantra (12 gnomon dials that measure ecliptic coordinates of stars, planets and all 12 constellation systems)
  •    Shastansh Yantra (next to Vrihat Samrat Yantra, this instrument is a 60-degree arc built in the meridian plane within a dark chamber. At noon, the sun's pinhole image falls on a scale below enabling the observer to measure the zenith distance, declination, and the diameter of the Sun.)[11]
  •    Unnatasha Yantra (a metal ring divided into four segments by horizontal and vertical lines, with a hole in the middle; the position and orientation of the instrument allows measurement of the altitude of celestial bodies)[10]
  •    Vrihat Samrat Yantra (world's largest gnomon sundial, measures time in intervals of 2 seconds using shadow cast from the sunlight)
  •    Yantra Raj Yantra (a 2.43-metre bronze astrolabe, one of the largest in the world, used only once a year, calculates the Hindu calendar)[12]


These instruments are huge structures and the scale to which they have been built intends to increase their accuracy. The Jantar Mantar was declared a national monument in 1948 and is managed under the Archeological Sites and Monuments Act of Rajasthan and protected as a National Monument. It is open to visitors from 9.00 am to 5.00 pm daily. Exploring this monument can take about 40-50 minutes. Visiting the Jantar Mantar during mid-day is most advisable and an overhead sun can help in understanding the way to take readings using each instrument.

Original Post