Length Units in Jaina Astronomy

The article "Length Units in Jaina Astronomy" by Sajjann Singh Lishk and S. D. Sharma examines the diversity of length measures in ancient Indian astronomy, focusing on the post-Vedanga pre-Siddhantic period. The main argument is that three different Jaina systems of measurement—the atma, utsedha, and pramana systems—coexisted, leading to significant variations in the magnitude of units like the yojana and creating confusion when relating them to British miles. The evidence is drawn primarily from Jaina canonical texts such as the Anuyogadvara Sutra (ADS) and the Tiloya Pannatti (TP), alongside comparative data from other traditions including the Paulisa Siddhanta (PS), Siddhantic units, the Buddhist Lalita-vistara, and reports by Megasthenes and Strabo. The authors demonstrate that a pramana unit equals 500 atma units or 1000 utsedha units, and that a yojana consistently contains 768,000 angulas across these Jaina systems. However, when comparing these to other texts, the Buddhistic kosa contains 1000 dhanusas instead of 2000, and the Buddhistic angula contains 7 yavas instead of 8, resulting in a Buddhistic yojana being half or one-seventh the size of a Jaina yojana depending on the conversion. The article also details the fluctuating estimates of the yojana's length in British miles, ranging from 4.5 to 16 miles according to various scholars like Dvivedi, Alberuni, and Fleet, and uses astronomical calculations, such as the Sun's declination and distance from the axis of Meru, to test these values. The authors conclude that careful attention to the specific system of measurement is essential to avoid misinterpretation of ancient distances, as the numerical relationships between the three Jaina systems persisted even as their actual physical lengths changed over time.

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