The Misra Yantra, one of the instruments in Jantar Mantar is meant to determine the shortest and longest days of the year.

Jantar Mantar, built by Maharaja Sawai Jai Singh II of Jaipur, is an important landmark of Delhi and is a unique edifice. The observatory is situated in the heart of Delhi's commercial centre near Connaught Place in India.

Other yantras in the observatory are also meant for the study of celestial bodies, plotting their course and predicting eclipses.