When The Zero Degree Meridian of the Ancient World Passed Through India

In school, we all learn about the Greenwich Meridian and Greenwich Mean Time. We are also informed assiduously that Greenwich is not to be pronounced as Greenwich but as Grenich. And thus, we Indians struggle with another English word that is spelled in one way and pronounced in another.

What many people do not know is that Greenwich in the United Kingdom became the zero-degree longitude of the world less than 150 years ago. Before that, for thousands of years, the prime meridian of the ancient world passed through the city of Ujjayani, now called Ujjain (also known as Avanti in ancient times) in the Indian state of Madhya Pradesh.

The capital of great kings such as Vikramaditya, the grand city was an acclaimed centre of astronomical study. The oldest text on astronomy in the world Surya Siddhanta refers to Avanti as the Prime Meridian. The text also lists Rohtak, Kurukshetra, and Lanka among the places lying on the zero-degree meridian. Lanka was regarded as the city at the intersection of the Equatorial line and the Prime Meridian. Today’s Sri Lanka is not the one referenced in the ancient texts, according to Indian astronomers.