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SOME UNIQUE FEATURES OF THE JAINA SCHOOL
OF ASTRONOMY
Sajjan Singh Lisbk
1. There existed in Atharva Veda Jyotişa, a thirty-fold division's system of time-units which may be conveniently called as "Trigesimal system'. Jaina astronomical system rendered a great role in the profitable conversion of Trigesimal system into Sexagesimal system of time-units,
There existed three unique systems of length-units viz. åtmā, utscdha and Pramana systems. The mystery of diversity of relationship between a yojana and the number of British miles is revealed out. Besides, Jainas had evolved a system of arc division or graduation of the zodiacal circumference. It was divided into poezi days and then 588 muhartas of a nakşatra month (lunar sidercal month) and subsequently in 54900 gagana-khandas (celestial parts) and 360 saura days leading to the concept of 360 modern degrees of arc.
2. Jainas had regarded earth as made up of concentric rings of land masses alternatively surrounded by ocean rings. The two suns, two moons etc move diameterically opposite about the mount Meru placed at the centre of Jambudvipa (the isle of Jambu tree), the central island of earth. The tentative astronomical model af Meru was purposefully designed such that its dimensions fit into certain astronomical constants e.g. obliquity of ecliptic.
3. The time of day was measured and the seasons were determined through the science of sciatherics.
4. Kinematical studies of sun and moon were distinctly made and the notion of declination was developed as implied in the concent of mandalas (diurnal circles) of sun and moon.
5. Jainas had attempted to reform the Vedanga Jyotişa quinqu. ennial cycle. An extensive study of zadkiel (pancanga or five pa: ts viz. tithi i.e. lupar day, day. karana i e. half lunar day. pakşatra i.e. asterism and yoga i.e. combination) was also made. Nakşatras (asterisms) were classified into kula category), upkula (sub-category) and kulopakula (Sub-sub-category) nakşatras dependiog upon their positions with respect to moon's position among asterisms at syzygies.
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