Main Characteristics and Achievements of Jaina School of Ancient Indian Astronomy

Summary

Focusing on the post‑Vedāṅga, pre‑Siddhāntic era of Indian astronomy, this paper highlights distinctive features of the **Jaina school of astronomy**. The author notes that Western histories often attribute Indian astronomical advances to Greek or Mesopotamian influences; however, Jaina texts exhibit indigenous innovation. Canonical works describe a unique cosmography: the universe is envisaged as a circular flat earth encircled by rings of mountains; there are two suns and two moons; and the moon is situated eighty yojanas higher than the sun. Jaina scholars devised an elaborate classification of time‑units culminating in a thirty‑fold division of time and a system of length‑units not found in Brahmanical or Buddhist literature. Through gnomon experiments they measured shadow‑lengths to construct sundials, determined solstices and equinoxes and standardised the duration of a **muhūrta** (48 minutes). They also introduced a quinquennial cycle to reconcile solar and lunar calendars and classified lunar months into *kṣaya*, *vriddhi* and *adhika* types. The essay surveys further achievements: calculation of declination and latitude; understanding of heliacal conjunctions and first visibility of planets; classification of eclipse cycles based on 40‑ and 48‑year periods; and measurement of celestial distances by projecting terrestrial distances onto the sky. Later sections discuss how Jaina observations of celestial colours aided in predicting rainfall and how their division of the zodiac into time‑degrees anticipated later Siddhāntic astronomy. The author concludes that these innovations were largely independent of foreign influence and that Jaina contributions prepared the ground for later developments in Indian mathematical astronomy.