Ujjain is literally the crossroad of Space and Time in India. This renowned and ancient city is famous for spiritual as well as scientific reasons. It has stood, quite literally, at the very centre of the development of astronomy as a science, as well as an instrument of spiritual knowledge and practice. It is the cradle of the Hindu science of astronomy and Timekeeping, and the principal seat of astronomical knowledge during its early history. It occupied this position because it is situated where India’s ancient Prime Meridian and the Tropic of Cancer once crossed.
In 1884, Greenwich became universally accepted as the prime meridian, the international standard for 0° longitude from where all world time is calculated. Before that, Ujjain was considered the central meridian for time in India. Even today, wherever you may be born, when a panchang or horoscope as per the Hindu almanac is drawn up, it is always based on Ujjain time (roughly 29 minutes behind IST).
As per the Surya Siddhanta, a 4th-century astronomical treatise, Ujjain is geographically situated at the precise spot where the zero meridian of longitude and the Tropic of Cancer intersect. From the text it is clear these methods were already thousands of years old at the time of its composition. Indicating the great age of India’s zero longitude, or Prime Meridian, of Avanti, the ancient name for the historic city of Ujjain 23°10’58”N & 75°46’38”E.
A Prime Meridian is an imaginary line drawn between the North and South Pole. A Prime Meridian is a meridian in a geographical coordinate system at which longitude is defined to be 0°. Together, a prime meridian and its antemeridian form a great circle. It is a zero point for both time and geographical calculations. Today the internationally accepted Prime Meridian runs through Greenwich, in England.
In India this line was always drawn through Ujjain. This is stated in all ancient texts on astronomy, as well as in the epics Mahabharata and Ramayana etc. It is what made Ujjain a very sacred city. Dedicated especially to Sacred Time. The main Shiva temple here is dedicated to Mahakala, Great Time. All Indian traditional calendars and all sacred time is calculated from this line.
One of the 12 jyotirlingas in the country and among the most prominent temples in Ujjain, Mahakaleshwar Temple is dedicated to Lord Shiva. The lingam (a symbolic representation of Lord Shiva) at Mahakaleshwar resides in a subterranean chamber and is believed to be swayambhu or self-manifested. The present temple is a five-storey structure and was constructed midway during the 18th century. Built in Bhumija, Chalukya and Maratha styles of architecture, the temple is an architectural marvel.
Because of its status as the centre for all astronomical and geodetic calculations, Ujjain attracted many religious and scientific institutions. Many of its temples are in some way connected to Time and Space. In the 18th century one of the still existing observatories for astronomy was build here by Maharaja Jai Singh II in 1725. Known as the Vedh Shala or Jantar Mantar it consists of 13 architectural astronomy instruments that measure many astronomical phenomena with great accuracy.
This observatory (vedhshala) measures time and altitude, determines eclipses, and studies the motions and orbits of planets. All the yantras (instruments) work on the principle of casting shadows.
Shankhu Yantra is a vertical gnomon (part of a sundial that casts a shadow) on a circular platform that calculates the length of the day. The Karka rekha (Tropic of Cancer), Makar rekha (Tropic of Capricorn) and Bhoomadhya (Equator) are marked by lines, and the gnomon’s shadow signals the equinoxes and solstices.
Samrat Yantra or sundial tells the time. A long flight of steps in the middle of the instrument casts a shadow on two walls on either side. The upper planes of the walls are parallel to the axis of the Earth, which is tilted at 23 degrees and 27 minutes with respect to its orbital plane.
Digansha Yantra calculates the altitude or distance from the horizon of any celestial body and its azimuth, or angular distance from the east or west measured along the horizon. It helps to gauge which planet is transiting from which nakshatra (celestial house) to another and its distance from Earth.
Nadi Valay Yantra calculates whether a celestial body is in the northern or southern hemisphere. Constructed in the plane of the equator, it has a northern and southern disc. These are illumined by the sun for six months each according to its position in the sky.
Bhitti Yantra or the transit instrument, is unique to Ujjain’s Vedshala. It measures the zenith distance of any celestial body with respect to Earth.
Taramandel The small planetarium (taramandel) has 20- and 30-minute shows for visitors on planets, stars, constellations, and galaxies.
In 1923, the Ujjain observatory was renovated by Maharaja Madhav Rao Scindia of Gwalior. Astronomical studies are still conducted here and an ephemeris, a journal showing the daily speed and position of the planets, is published annually.
UJJAIN: AT THE CROSSROADS OF TIME : Outlook Traveller
Ujjain, Crossroad of Space and Time : http://www.chidambaramhiddentreasure.com/
Amazing India Ujjain The Meridian of The World Amazing India – Art of Living – Bharath Gyan