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A Concise History of Science in India c6.s2: Late Vedic and Pre-Siddhāntic Astronomy, Jaina Astronomy

A Concise History of Science in India c6.s2

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English

Contents

Late Vedic and Pre-Siddhāntic Astronomy, Jaina Astronomy

c6.s2.1

In connection with our discussion of astronomical knowledge in the *Saṃhitās* and the *Brāhmaṇas*, we have several times referred to the *sūtras* and the *Vedāṅga Jyotiṣa* because the latter by and large embodied the astronomical knowledge already found in the Vedic period proper. But the late character and composition of the *sūtras* and the *Jyotiṣa* are not in doubt. The *Vedāṅga Jyotiṣa* records the location of the summer and winter solstices in the middle of *Āśleṣā* and beginning of *Dhaniṣṭhā*. From the present positions of the solstices in the asterisms and from the precessional rate of 1° for every 72 years, it is easy to show that at about 1400 B.C. the solstices coincided with the middle of *Āśleṣā* and the beginning of *Dhaniṣṭhā*. This has led many scholars to suggest 1200 B.C. as the time of composition of the *Vedāṅga Jyotiṣa*. But the possibility of an earlier tradition being recorded in the *Jyotiṣa* and other internal and literary evidence strongly suggest it to be a work of the *Sūtra* period, that is after 700 or 600 B.C. (Filliozat placed it between 400 B.C. and A.D. 200). The work is attributed to Lagadha who probably recast it from an earlier work.

The Vedāṅga Jyotiṣa

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The *Vedāṅga Jyotiṣa*a teaches a five-year luni-solar cycle (*yuga*). At the beginning of the cycle, the sun and the moon lie at the starting point of the *nakṣatra Dhaniṣṭhā*. During this period the sun goes round the circle of asterisms 5 times and the moon 67 times. This means that the period has 67 sidereal months and 62 synodic months. Moreover, a solar year has 366 *sāvana* or civil days and the five-year cycle 1,830 *sāvana* days. A synodic month has 30 lunar days or *tithis*, so that a five-year cycle has 1,860 lunar days. These elements give the length of a sidereal month as 27·31 and that of a synodic month as 29·52 *sāvana* days. To summarize these elements, one quinquennial cycle contains

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5 sun's revolutions;
67 moon's sidereal revolutions or months;
62 moon's synodic revolutions or months;
1,830 *sāvana* or civil days;
1,835 sidereal days;
1,800 solar days;
1,860 lunar days or *tithis*.

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The *Jyotiṣa* divides a *sāvana* day into 30 *muhūrtas*, 1 *muhūrta* into 2 *nāḍikās*, 1 *nāḍikā* into 10 1/20 *kalās*, 1 *kalā* into 124 *kāṣṭhas* and 1 *kāṣṭha* into 5 *akṣaras*. This makes a *sāvana* day equal 603 *kalās* and a lunar day (*tithi*) 593 17/62 *kalās*. The duration of a *nakṣatra* is 610 *kalās*.

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a *VJ.*, 28–31.

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The above elements and the measures have been utilized in calculating the places in the circle of asterisms where the new and the full moon take place during the whole quinquennial cycle. From the explanation given by Thibaut, it appears that each *nakṣatra* space (13° 20') was further subdivided into 124 parts, and the positions of the new and the full moon were given in terms of the *nakṣatra* and its subdivisions.a This is a clear indication of the scientific use of the stellar zodiac for calculating the positions of the sun and the moon.b

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In the *Jyotiṣa* we also find for the first time the rule for determining the length of the day between the two solstices. The shortest day is given as 12 *muhūrtas* at winter solstice and the longest as 18 *muhūrtas* at summer solstice. In one *ayana* of 183 days, the day length is said to increase or decrease by 6 *muhūrtas*, whence the daily increase or decrease works out to 6/183 or 2/61 *muhūrta*.

Some Ancient Astronomers of this Period

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Varāhamihira, in his *Bṛhatsaṃhitā*, has recorded the names of a large number of astronomers of this period. Some of them are Garga, Parāśara, Kāśyapa, Nārada, Pitāmaha, Sūrya, Puliśa, Vasiṣṭha, Romaka, Viṣṇugupta, Asita-Devala, Ṛṣiputra, Bhṛgu, Maya, Bādarāyaṇa, Nagnajit and so on. Most of them are mentioned only in name. Passages attributed to some of them are quoted particularly by Varāha's commentator Utpala, but the works of the majority of them are no longer extant. The teachings of Pitāmaha, Sūrya, Puliśa, Vasiṣṭha and Romaka have been summarized by Varāha in his *Pañcasiddhāntikā* about which we shall speak later. Among the others, the most important are Garga and Parāśara, both of whom compiled *saṃhitās* known after their names. The astronomical knowledge presented in these *saṃhitās* is more or less the same as found in the *Vedāṅga Jyotiṣa*. It is, therefore, no wonder that Somākara, the commentator of the *Jyotiṣa*, quotes extensively from Garga in his exposition of the *Jyotiṣa*.

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Garga is also important from the viewpoint of his frequent references to the Greeks (*yavana*), and to the excellence of the astronomical science as studied among their savants. ‘The Greeks are indeed *mlecchas*, but amongst them this science (astronomy)’, writes Garga, ‘is well established; therefore even they are honoured as *Ṛṣis*.’ From his references to the fiercely fighting Greeks who penetrated into the heart of Hindusthan (*madhyadeśa*), Kern concluded that Garga lived probably during the period of conquests of the Bactrian Greeks (third to second century b.c.). Parāśara who figures prominently in some of the *Purāṇas* is probably posterior to Garga.

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a Thibaut (2), pp. 411-37.

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b Shamashastry has interpreted such divisions as giving a method of ascertaining readily *parvatithis* and *nakṣatras* (*see* his edition of the *Vedāṅga Jyotiṣa*, Mysore, 1936).

Jaina Astronomy

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We have already referred to the Jaina interest in astronomy. *Jyotiṣa* appears quite early in the history of their religious literature and forms an important branch of their study as we know it from the *Bhagavatī-sūtra* and the *Uttarādhyāyana-sūtra*. Śānticandragaṇa, in his preface to his commentary on the *Jambūdvīpaprajñapti*, states that the knowledge of astronomy was an indispensable accomplishment on the part of a Jaina priest who was to decide the right time and place for religious ceremonies. Although the Jainas developed a set of peculiar cosmographical theories which came in for sharp criticism at the hands of Brāhmaṇa astronomers, they adopted and followed, with minor variations, the Brāhmaṇic astronomy of the *Vedāṅga Jyotiṣa*.

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The principal source of Jaina astronomy is *Sūryaprajñapti*, a work divided into 20 books and written in *ardhamāgadhī prākṛt*, which is extant with an elaborate commentary by Malayagiri. Free from Greek influence, the work was probably written a few centuries before the Christian era. Its authorship has been attributed to Mahāvīra. The next important astronomer was Bhadrabāhu (d. 298 B.C.), a *śrutakevalin* and a prominent personage in the history of Jaina religion. He is believed to be the author of a commentary on the *Sūryaprajñapti* and of an astronomical *saṃhitā* known after his name, of which only fragments have been preserved in later commentaries. Then we have the *Jambūdvīpaprajñapti* with a number of commentaries, of much later date, where elaborate descriptions of the different *dvīpas* of the Jaina cosmography are met with.

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The peculiarity of the Jaina astronomy consists in its conception of two suns, two moons and two sets of 27 *nakṣatras*. This conception is a consequence of the Jaina cosmography according to which the earth is regarded as a series of flat concentric rings of land masses separated by concentric ocean rings. The central circle *Jambūdvīpa*, with the mountain *Sudarśa Meru* in the centre, is encircled by the salt ocean. Beyond it lies the *Dhātukī Dvīpa* encircled by the black ocean *Kālodadhi* and beyond that the *Puṣkara Dvīpa* rimmed by an impassable mountain range, the *Mānuṣottara Parvata*. The innermost *Jambūdvīpa* is divided into four quarters, of which the southernmost part is *Bhāratavarṣa* (India). The sun, the moon and the stars are assumed to move in circles, parallel to the earth's surface, round Mount Meru as centre. As *Jambūdvīpa* is divided into four quarters and four directions, and as the sun should make day in succession to the regions south, west, north and east of Meru, the sun's diurnal orbit is also divided into four quarters. Since the length of a day, disregarding variations, is 12 hours or 15 *muhūrtas*, the same sun after making day over *Bhāratavarṣa* in the southern quarter cannot reappear on the following morning as it still has three quarters to travel. To obviate this difficulty, the theory supposes two similar suns, ***Bhārata*** and ***Airāvata***, separated from each other by half the orbit, to describe the whole orbit. In this process each sun makes day over *Bhāratavarṣa* on alternate days.

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This is given in the *Sūryaprajñapti* with Malayagiri's commentary as follows:a

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'There are two suns, Bhārata and Airāvata. They both move through half a diurnal circle in the course of 30 *muhūrtas*; i.e. in the course of 60 *muhūrtas* or 2 days, they complete a full diurnal circle. That sun which moves in the outermost circle in the southern hemisphere is called Bhārata, because it illumines the Bhāratakhaṇḍa. The other which moves through the same outer circle in the northern hemisphere is called Airāvata, because it illuminates the Airāvata area.'

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To explain the variations of day length, 183 diurnal circles are imagined. Each sun after rising in the first circle rises in the next circle each following morning, increasing the day-length in the *uttarāyaṇa* and decreasing it in the *dakṣiṇāyana* by 6 *muhūrtas*, as taught in the *Vedāṅga Jyotiṣa*.

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For calendrical purposes, the *Sūryaprajñapti* adopts the five-year cycle beginning with the summer solstice when the full moon takes place at the *nakṣatra Abhijit*. Such a five-year cycle or *yuga* has 1,830 *sāvana* days, 1,800 'solar' days, 1,860 *tithis*, 60 solar months, 61 *sāvana* months, 62 synodic months and 67 sidereal months. Thus a year consists of 366 *sāvana* days. The year having 360 solar days is called a *ṛtu* year. The calendar also recognizes a lunar year of 354 12/62 days and a *nakṣatra* year of 327 51/67 days, giving the lengths of a synodic and a sidereal month as 29 32/62 and 27 21/67 days respectively. The year is divided into 2 *ayanas* of 183 days each.

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The ecliptic is divided into 28 unequal spaces, beginning with the *nakṣatra Abhijit*. The scale conforms to the sidereal month-length and the circle is divided into 27 21/67 parts. The *Sūryaprajñapti* contains the statement that the planets travel faster than the sun and the stars, the sun slower than the moon and the stars faster than the *nakṣatras*. Regarding the apparently awkward last statement, Kaye thinks that the motion of the stars with regard to the fixed *nakṣatras* which are here used as a sort of zodiacal scale of reference probably means their precession with respect to equinoxes.b

Cites (7)