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Now we come to our proper subject of Astronomy and Astrology. According to the Jains the heavenly bodies are separate worlds similar to ours inhabited by creatures called Jyotishka or luminary gods having human form but possessing supernatural powers. They are of five kinds, ie, the Suns, the Moons, the planets, the conslellations and miscellaneous stars. They in their vimanas revolve round the Meru mountain over the regions inhabited by man and make it possible to measure time. With other aspects of these gods, such as their birth, age, bodily stature, physical power, their stately magnificence, their nature, their religion, their relation with man etc. we are not concerned here.
The Jains in common with the Puranas regard the earth to be a flat and circular surface surrounded alternately by innumerable rings of seas and continents This view of the Jains has been characterised as fanciful by Bhaskaracarya in his Siddhanta-siromani who held that the earth was a sphere.
As regards the orbits of the planets the Jains conceive them to be cuncentric circles ( #lea) separated by equal spaces. The opinion that the mandalas were spiral is also recorded in the Jain sutras. The method of reckoning time also is peculiar to the Jains. In some respects it resembles that found in the Jyotirvedanga. The following points are worth noting :--
1. The Jaina calculation of time 18 based on a 5-yearly yuga containing 60 months or 1830 days. This makes a year to be of 306 days and a month of 30 days.
2. The begininng of the yuga is marked by
(a) the sun's commencement of its journey to the south (rerurta ),
(b) the moon's course being northward ( FETTU ), (c) the tithi being the first of the dark half of Sravana (d) the Karana being Balava, and (e) che nakshatra being Abhijit.
? A yuga contains 62 luner months, (candramasa) each of 2941 solar days.
4. A lunar year (candravarsha) contains 354}i solar days.
5. A tithi is a lunar day (candra dina) of 298i muhurta or 59:4 ghatikas.