The Jaina School of Astronomy (Part II) - The Theory of the two Suns
By Sukumar Ranjan Das
Summary
This continuation of a series on Jaina astronomy explores doctrines recorded in medieval treatises about the movement of the sun. The article summarises the Jaina belief in two suns: one moves above the horizon while the other travels below, emerging after the first sets. The author analyses a passage describing how the sun traverses a circular path divided into arcs associated with different continents and oceans and computes the length of a solar year according to Jaina calculations. He compares these results with those of Āryabhaṭa and later Hindu astronomers and notes that the Jainas adopted a geocentric model with nine regions. Diagrams illustrate the orbit of the sun and the positions of the two suns at dawn and dusk. The article discusses theories on sunrise and sunset, the apparent slow motion of the sun at the solstices and the concept of ‘two suns’ as symbolic of day and night rather than distinct celestial bodies.
Conclusion
The author concludes that Jaina astronomers developed an internally consistent cosmology rooted in religious cosmography. Their notion of two suns provided a mythic explanation for diurnal cycles and their numerical parameters, though not always accurate by modern standards, show considerable ingenuity. Recognising these ideas enriches our understanding of India’s multi‑faceted astronomical traditions.