Janta Manta: some reflections

by Michelle

Jai Prakash at the Delhi Observatory

Recently, whilst in India, I visited Janta Manta, a collection of architectural astronomical and astrological instruments built from stone, marble and bronze tablets by Maharajah Jai Sing II between 1727 and 1724. In all he established five observatories, including the ones in Jaipur and Delhi. The concept was partly inspired by the Mughal emperor, Muhammed Shah, who lived in Fatephur, Agra, a city constructed by the emperor Akbar.

The purpose of the Janta Manta scapes was to revise the calendar and astronomical tables, to predict the times and movements of the sun, the moon and the distant planets. An astrological, and spiritual significance is inherent in these structures, the ancient Indian astronomers, being Jyotisa masters. Jyotisa astrology differed from its Hellenistic counterpart, deriving from the Vedas its central theme of the bandhus, or bonds between the inner and outer world; between microcosm and macrocosm. In Jyotisa astrology there are lunar mansions, nakshatras, among the twenty seven divisons of the sky. According to Jyotisa, the 360 bones of the fetus are derived from 360 days, fusing into 206 adult ossicles. Embryological evidence doesn’t confirm this numerically, but the principle of fetal to adult bony fusion is correct.

Among the structures in Janta Manta Hindu chhatris, or cupolas, reach skyward, positioned as platforms for announcing  the eclipses, and the monsoons.

Jai Prakash: New Delhi observatory

Samrat Yantra, the giant sundial, Delhi Observatory


Samrat Yantra means “Supreme instrument”, a giant triangle, or sundial , it has a 128 foot long hypotenuese which is parallel to the earth’s axis and points to the northern pole. It’s the world’s largest sundial; its shadows move at 1 mm per second, which over the course of a minute, is a visually arresting experience, for the observer.

Subsidence of the structures, and the variable width of the sun’s penumbra limit the accuracy of these incredibly beautiful ancient instruments, although the Samrat Yantra can be used to tell local Jaipur time, to an accuracy of a few seconds. From Janta Mantar, the ancients tracked the stars, and calculated the eclipses, altitudes and collisions of the celestial bodies, as a way of understanding natural events, history and the conditions of their lives.