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 four-monthly 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 Jyotisa-Vedangas, 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 termnaksatra-darsa 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 parts-the 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 time-reckoning. 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 month-reckoning, 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 well-known 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 star-groups, and any of the 27 equal divisions of the ecliptic, each distinguished by a determinant star (yoga tara). Derived from nakta-tra, it means `guardian of night', that is stars or star-groups, 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 ë 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 Rahu-ketu 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 Rahu-ketu 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 astam-yan (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 lunar-month 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.