Surya Siddhanta: The Startlingly Accurate Astronomy Book of the 1st Millennium BC

Many people know the deeds of Ravana, the captor of Sita in the Indian Epic the Ramayana; however, less well known are the incredible accomplishments of his father-in-law, King Maya. According to legend, the Hindu Sun god, Surya, revealed to Maya highly specific knowledge of the cosmos, presumably to allow the people of Earth to better worship him. This series of treatises is known as the Surya Siddhanta and it is the oldest book of astronomy known to exist. It is startlingly accurate.

The Surya Siddhanta is an incredible testament to the advanced thinking of ancient Indians. In this text, one can find the roots of trigonometry as well as essential mathematical inventions such as standard notation and the decimal system. In addition, the text describes gravity over a millennium before Sir Isaac Newton developed his theory in 1687. It explains sidereal revolutions and how planets move eastward. It accurately calculates the size and position of distant planets, the length of a tropical year, and the amount of time that has passed since creation. Finally, in its discussion of how time passes at different rates under different circumstances, it contains the seeds for relativity.

The mean (circular) motion of planets according to the Surya Siddhantha.

Hindu lore has it that the Surya Siddhanta is 2 million years old. Vedic tradition holds that, in an oral form, it was first composed 2500 years ago. Modern scholars think that it was most likely composed sometime during the early 6th century AD. Holding aside the possibility of divine inspiration, many believe that the wisdom found in the Surya Siddhanta came from a confluence of Indian and Greek thought, which came together during the Hellenistic Age. In particular, the work of Hipparchus seems to have had a significant impact on Indian thought.

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