VEDIC ASTRONOMY (OR PRE SIDDHANTHIC ASTRONOMY)

Part I: References to Astronomy/ astronomical phenomena in Vedas and Vedic literature:

Like in any other civilization Astronomical concepts were found in ancient Indian texts. Stray references to astronomical concepts are found in Vedas and other ancient Indian literary texts. Vedic texts are repositories of several mythologies developed around stellar constellations. References to planets, nakstras, motion of Sun and moon are found in Rig Veda. The details of darsapurnamasa, i.e. the new­ and full­ moon sacrifices, the caturmasya or four­monthly sacrifices, seasons, months and month names, are stated specifically in Yajurveda. The importance of the winter solstice is emphasized through the mahavrata rites which are also dealt with at length in the Brahmanas of the Samaveda. The Atharvaveda also contain stray passages of astronomical consequence, such as the solar eclipse, the mention of Rahu for the first time, intercalation with a thirteenth month and a list of 28 naksatras including Abhijit.

As part of the Vedic corpus we have two Jyotisa­Vedangas, one in the Yajurveda recension containing 43 verses and the other in the Rgveda recension containing 36 verses, dealing exclusively with astronomy. The Vedanga Jyotisha, is an Indian text on Jyotisha (Indian astronomy), redacted by Lagadha. The text is foundational to the Jyotisha discipline of Vedanga, and is dated to the final centuries BCE. The text describes rules for tracking the motions of the sun and the moon. In the Vedanga Jyotisha Lagadha praises astronomy as the crowning subject in the ancillary Vedic studies. In explaining the scope of astronomy, the Vedanga Jyotisa states: ‘The Vedas are revealed for the purpose of performing sacrificial rites; these rites are laid down in order of time. Therefore, he who is versed in astronomy, the science of the reckoning of time, knows the sacrifices.’ In the Mundaka Upanisad astronomy is included in the list of several branches of Vedic studies. In the Brahmana literature, we come across the termnaksatra­darsa meaning ‘a star gazer’ or ‘a gazer at the lunar mansions’. This term has also been used sometimes to mean an astrologer. Another term used to refer to an astronomer is ganaka which literally means ‘a calculator’ or ‘a mathematician’. The use of these two terms appears to imply the study of astronomy both from the practical (observation of stars) and theoretical (calculation) considerations. In the vedic texts, the universe was conceived as of three distinct parts­the earth (prithvi), the firmament (antariksa) and the heavens (dyaus). The Sun was regarded as the most important heavenly object and its path, the ecliptic, was considered sacred. The Moon was the next most important and became the obvious choice for time­reckoning. It was referred to as masakrt (‘maker of the month’) – the interval between two consecutive new moons or full moons was taken to be ‘month’. There were two systems of month­reckoning, namely, the amanta and the purnimanta, ending with the new moon and the full moon, respectively. The Moon’s path was observed in relation to the 27 or 28 naksatras or asterisms and the lunar zodiac was well determined. There is no denying the fact that, although there were lunar zodiac presentations in Babylonia, China and Arabia, the method and the manner adopted by the Vedic texts unmistakably point to their originality. The names of the lunar months were given on the basis of the naksatra in which the full moon occurred. The twelve lunar months were divided into six seasons of two months each. There were also special names for the solar months.

There are several references in the Rgveda and in the Brahmanas of the later ages to the sun’s path through the heavens. It is stated that Varuna, the chief of the Lords of natural order, has made a spacious pathway for the sun to travel, Zodiac. Observation of the solar eclipse is recorded in several places in the Vedic literature. The well­known Svarbhanu legend is one excellent example of description of the solar eclipse with flurish. According to its earliest Rgvedic version, Svarbhanu, the asura, pierced the sun with darkness so completely that the bewildered inhabitants on the earth did not know where they were standing. Then Atri, with the power of his prayer, caused Svarbhanu’s magic arts to disappear and restored the sun to its brilliance. Pancavimsa Brahmana, of which a typical description runs as follows: ‘The Daemoniac Svarbhanu struck the sun with darkness; the Gods did not discern it (the sun hidden as it was by darkness); they resorted to Atri; Atri repelled its darkness by the bhasa. The part of the darkness he first repelled its darkness he first repelled became a black sheep, what (he repelled) the second time (became) a silvery (sheep), what (he repelled) the third time (became) a reddish one, and with what (arrow) he set free its original appearance (colour), that was a white sheep.’ The interesting feature of the above passage is the detailed observation of the change of colour in the sun’s disc during the progress of an eclipse.

The antiquity of the Indian naksatra system has been traced to the Rgveda, where the term naksatra has been used both in the sense of stars and lunar mansions. While the naksatras are doubtless mentioned in the Rgveda, their whole series, numbering 27 or 28 and headed by Krttikas, turns up for the first time in the Yajurveda. In the Vedic literature the term naksatra has been used to indicate both asterisms, stars or star­groups, and any of the 27 equal divisions of the ecliptic, each distinguished by a determinant star (yoga tara). Derived from nakta­tra, it means ‘guardian of night’, that is stars or star­groups, and in this sense the word must have been used at the beginning. Later on, naksatra meant one of the 27 equal parts, that is a space of 13 º 20’ of the ecliptic.

In vedic literature the moon, the most conspicuous object in the night sky, receives such appellations as candra, candramas and soma. It has no light of its own, but assumes ‘the brilliancy of the sun’ or ‘is adorned with Surya’s arrowy beam’, that is it shines with the borrowed light of the sun.

The study of planets appears in late astronomical works. The Vedanga Jyotisa does not mention them. However, names of planets like Jupiter finds a place in the Vedic corpus. In the Maitrayani Upanisad, planets (graha) are mentioned. To the seven planets, including the sun and the moon, the Indians added Rahu and Ketu, to formulate their Rahu­ketu theories of eclipses. The word Rahu, in the sense of a planet, appears in the Atharvaveda and the Chandogyopanisad apparently with no astronomical meaning, but in the Yajnavalkyasmrti it does so in the astronomical sense (as ascending node). The word ketu also appears in the Atharvaveda in the sense of any unusual or striking phenomenon such as comet, meteor or a falling star. Astronomical samhitas, however, do not mention ketu as a cause of eclipse. Rahu and ketu, along with planets, are mentioned in the mahabharata, though Ketu is omitted in the Ramayana. From Varahamihira onwards, in true astronomical circles, Rahu and Ketu meant the ascending and the descending node respectively of the moon. It is in the subsequent Puranic period the Rahu­ketu theories of eclipses were formulated.

Ancient Indian Astronomy is based upon sidereal calculations. The sidereal astronomy is based upon the stars and the sidereal period is the time that it takes the object to make one full orbit around the Sun, relative to the stars. Both ‘day’ and ‘night’ appear as natural unit of time in the earliest literary productions of the Indians. Expressions like ‘many dawns and nights’, ‘days subdue the nights’ occur in the Rgveda. Day, that is the bright half, was divided, according to the Atharvaveda and the Taittiriya Brahmana, into five parts, e.g udyan suryah (rising sun), samgava (gathering of cows),madhyam­ dina (midday), aparahan (afternoon) and astam­yan (sunset). Further division of the day into muhurtas and still smaller units has been traced to the Brahmana period. According to the Satapatha Brahmana, ‘there are ten thousand and eight hundred muhurtas in the year (1 day = 30 muhurtas), and fifteen times as many Kisprus as there are muhurtas ; and fifteen times as many idani as there are etarhi; and fifteen times as many breathing as there are idani’.

In the vedic literature the month was again divided into two natural halves, the light half (sukla) from new to full moon and the dark half (krsna) from full to the new moon. A lunar­month was divided into two parts or paksas, the bright half and the dark half of one lunation, each paksa having 15 tithis, and ingenious devise, which is characteristically Indian, for calendrical purposes and the names of the paksa following the Sanskrit ordinals. A day was regarded as consisting of 30 muhurtas, (the longest at the summer solstice being 18 and the shortest at the winter solstice 12 muhurtas). Several passages in the Brahmanas point unmistakably to the knowledge of solstices among the Vedic times. .The increase of day­ length from winter solstice to summer solstice and the corresponding decrease in the duration of the night are recorded in the Jyotisa. Here the day has 30 muhurtas, the shortest day­ length at the winter solstice is given as 12 muhurtas and the longest at the summer solstice as 18 muhurtas. In the Jyotisa 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 muhurtas at winter solstice and the longest as 18 muhurtas at summer solstice. In one ayana of 183 days, the day length is said to increase or decrease by 6 muhurtas, whence the daily increase or decrease works out to 6/183 or 2/61 muhurta.

The year is divided into two halves of six months each marked by the winter solstice when the Mahavrata rites are performed and by the summer solstice when the Visuvat day is observed. This is also borne out by the well­known statement of the Vedanga Jyotisa­prapadyete sravisthadau suryacandramasavudak­(The sun and the moon turn north at the beginning of the naksatra Dhanistha). When the winter solstice lies in Dhanistha and the summer solstice in Maghas (14 naksatras ahead), the vernal equinox must lie in the Krttikas.

The Vedanga Jyotisa records the location of the summer and winter solstices in the middle of Aslesa and beginning of Dhanistha. From the present positions of the solstices in the asterisms and from the precessional rate of 1º for every 72 years, it is easy to show that at about 1400 B.C. the solstices coincided with the middle of Aslesa and the beginning of Dhanistha. This has led many scholars to suggest 1200 B.C. as the time of composition of the Vedanga Jyotisa. But the possibility of an earlier tradition being recorded in the Jyotisa and other internal and literary evidence strongly suggest it to be a work of the Sutra period, that is after 700 or 600 B.C.

From various stray statements in the Brahmanas, it is possible to infer that the Vedic Hindus recognized a lunar year of 354 days (12 X 29½), which was adjusted to the sidereal solar year of 366 days (Vedanga Jyotisa) either by adding 12 days each year or a thirteenth month of 30 days every 2½ years. The names of the lunar months were derived from the naksatras in which the full moon occurred, e.g. Phalguna, Caitra, Vaisakha, Jyaistha and so on from the naksatras Phalguni, Citra, Visakha, Jyestha respectively.

The Vedanga­jyotisa conceived of a cycle of five years, a luni­solar cycle called the yuga, at the beginning of which the Sun and the Moon would lie at the starting point of the naksatra Dhanistha. During this period, there would be 5 revolutions of the Sun, 67 Moon’s sidereal and 62 synodic months; 1830 savana or civil days; 1835 sidereal days, 1800 solar days and 1860 lunar days or tithis. The civil day was divided into 30 muhurtas: 1 muhurta into 2 nadika into 10 1/20 kalas; 1 kala into 124 kasthas; and 1 kastha into 5 akssras.

Part II Astronomical tradition in Jaina tradition

The Jainas also claim considerable antiquity for their interest in, and study of, astronomy. The four branches of their canonical texts include ganitanuyoga (principles of mathematics), samkhyana (arithmetic) and iyotisa (astronomy). Like the Brahmanas, the Jainas, too, demanded of their priests great proficiency in astronomy for the proper observance of their religious ceremonies.

Although the Jainas developed a set of peculiar cosmographical theories which came in for sharp criticism at the hands of Brahmana astronomers, they adopted and followed, with minor variations, the Brahmanic astronomy of the Vedanga Jyotisa. The principal source of Jaina astronomy is Suryaprajnapti, a work divided into 20 books and written in ardhamagadhi prakrt, 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 Mahavira. The next important astronomer was Bhadrabahu (d. 298 B.C.), a srutakevalin and a prominent personage in the history of Jaina religion. He is believed to be the author of a commentary on the Suryaprajnapti and of an astronomical samhita known after his name, of which only fragments have been preserved in later commentaries. Then we have the Jambudvipaprajnapti with a number of commentaries, of much later date, where elaborate descriptions fo the different dvipas of the Jaina cosmography are met with.

The peculiarity of the Jaina astronomy consists in its conception of two suns, two moons and two sets of 27 naksatras. 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 Jambudvipa, with the mountain Sudarsa Meru in the centre, is encircled by the salt ocean. Beyond it lies the Dhatukin Dvipa encircled by the black ocean Kalodadhi and beyond that the Puskara Dvipa rimmed by an impassable mountain range, the Manusottara Parvata. The innermost Jambudvipa is divided into four quarters, of which the southernmost part is Bharatavarsa (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 Jambudvipa 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 muhurtas, the same sun after making day over Bharatavarsa 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, Bharata and Airavata, separated from each other by half the orbit, to describe the whole orbit. In this process each sun makes day over Bharatavarsa on alternate days.

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 day­length in the uttarayana and decreasing it in the daksinayana by 6 muhurtas, as taught in the Vedanga Jyotisa.

Part III : Jothisa period gives way to Siddhanthic phase in Indian astronomy

While the astronomical computations enunciated in the Vedanga­Jyotisa continued to be in use for a long time, possibly during the few centuries preceding the Christian era, there was emerging a new class of astronomical literature called the Siddhantas. An important development was the gradual replacement of the naksatra system by the 12 Signs of the zodiac, Mesa, Vrsabha, Mithuna…..Mina, similar to the animistic notions of the Babylonians and from them of the Greeks. With the invasion of India by Alexander the Great in the fourth century B.C. and the subsequent Hellenic and the Hellenistic or Greco­Roman contacts with India, conceivably the astronomical elements of the former should have influenced the Indian culture­area.

The newly emerging siddhantas were in the nature of rules or the enunciation of methods for arriving at solutions of the concerned astronomical problems. According to the Indian traditional belief, there were principally eighteen such siddhantas, namely, and Surya, Paitamaha, Vyasa, Vasistha, Atri, Parasara, Kasyapa, Narada, Gargya, Marici, Manu, Angira, Lomasa (or Romaka), Paulisa, Cyavana, Yavana (or the Greek), Bhrgu and Saunaka. Five of these Siddhantas, viz., the Saura, the Paitamaha, the Vasistha, the Romaka and the Paulisa were ably codified by Varahamihira in his Pancasiddhantika (c. 505 A.D.) who has emphasized that the Saura was the most accurate of them all. With the emergence of Siddhanthic texts and schools, new heights were reached by Indian astronomy.