Length Units in Jaina Astronomy

Summary

Sajjan Singh Lishk and S. D. Sharma’s article investigates the measurement systems used in Jaina astronomical and cosmological texts. The authors note that ancient Indian astronomy employed various linear units (aṅgula, yojana, yūkā etc.) whose values differed across schools. Focusing on Jaina canonical literature from the post‑Vedāṅga and pre‑Siddhāntic period, they identify three distinct systems of length: a canonical system used in the cosmological works (where one yojana equals 4 krośas or 32,000 daṇḍas); a Purāṇic system (one yojana = 800,000 aṅgulas); and a Siddhāntic system (one yojana ≈ 5 miles). Within these systems, units such as hasta, aṅgula, utsedha and pramāṇa show varying ratios. The article reproduces tables comparing the value of yojana across nine sources, revealing that a yojana ranges from 4 to 8 miles depending on the text. For example, the Tiloyapaṇṇattī equates one yojana to 500 dhanus, whereas the Sūrya‑prajñapti uses 1,000. The authors explain that differences stem from the fusion of cosmological speculation and practical astronomy; canonical texts emphasised symbolic cosmography rather than precise geography. They highlight that Jaina cosmology divides the universe into three realms (adho‑loka, madhya‑loka, ūrdhva‑loka) measured in rājju (an immense unit), yet within these realms smaller units vary. By comparing with Buddhist and Hindu sources, the article shows that Jains sometimes adopted Brahmanical units but also developed unique scales. The authors caution that converting ancient units into modern miles is problematic because the same term (yojana) covers values from 4.00 to 8.00 miles. They suggest using internal ratios rather than absolute lengths to understand cosmographic models. The article concludes that the variety of units in Jaina texts reflects the coexistence of multiple traditions and underscores the need for careful methodological choices when interpreting ancient astronomy.