Bharatiya Jyotihshastra (History of Indian Astronomy), translated by R. V. Vaidya v1.c6.s2: The Yuga System of Measuring Time

Bhāratīya Jyotiḥśāstra (History of Indian Astronomy), translated by R. V. Vaidya v1.c6.s2

Language: English

The Yuga System of Measuring Time

v1.c6.s2.1

The measure (length) of the *Kaliyuga* is 4,32,000 years. Those of *Dvāpara*, *Tretā* and *Kṛta* are respectively twice, thrice and four times of this. These four *yugas* constitute the *Mahāyuga* and its measure is ten times that of the *Kaliyuga* and is equal to 43,20,000 years. One thousand such *Mahāyugas* make one *Kalpa*, which is known as *Brahmā’s* day. The *Kalpa* contains 14 *Manus*. So far, a period equal to 6 *Manus* and 27 *Mahāyugas* has elapsed from the commencement of the *Kalpa* up to the present *i.e.* the 28th *Mahāyuga*; and after passing through *Kṛta*, *Tretā* and *Dvāpara* of the current *Mahāyuga*, we are now passing through the *Kaliyuga*.

v1.c6.s2.2

71 Mahāyugas make one Manu and a period equivalent to a Kṛtayuga known as ‘Manu-sandhi’ (i.e., the transition period between two Manus), is reckoned in the beginning of each Manu period. This means that a period equal to 4567 Kaliyugas have elasped from the commencement of Brahmā’s day up to the present Kaliyuga. All Siddhāntas with the exception of that of Āryabhaṭa agree on these points, although they hold somewhat different views on other matters.

v1.c6.s2.3

According to the modern Sūrya-Siddhānta and Āryabhaṭa I, all the seven planets including the sun and the moon were together in the beginning of the present Kaliyuga. In other words, the mean longitude of each of these bodies was zero; but according to Brahmagupta and Āryabhaṭa II, all the planets had such a general conjunction only at the commencement of the Kalpa, and not at that of the present Kaliyuga when they were situated within a range of 3 to 4 degrees from one another. There is yet another divergent view which will be explained later on.

v1.c6.s2.4

This book relates the history of the study of the positions and motions of heavenly bodies and that of the development of the various aspects of astronomical knowledge in our country. The ancient name of our country is Bhārata Varṣa, Bhārata Khaṇḍa, or Bhārata. Because this book contains the history of astronomical science in our country, it is titled “Bhāratīya Jyotiṣa Śāstra—(its) Ancient and Modern History”.

v1.c6.s2.5

Saṃhitā and Jātaka, the two branches of astronomy, depend upon the motions of planets and stars. The chief aim of our astronomy is the prediction of actual planetary positions, that is foretelling what place in the sky a particular planet would be occupying at a particular time. Its complicatedness is inherent. An accurate knowledge of the mean motions and positions of planets emanates from an accurate knowledge of their true positions and motions. Even before they acquired the capacity to predict accurately their apparent positions, the ancients did possess a tolerably accurate knowledge of planets’ mean motions and positions. This was the preliminary stage. The Siddhāntas and other available astronomical works deal with the calculations of true positions and motions of planets. A considerable period of time must, however, have elapsed before man’s knowledge of astronomy reached that stage.

v1.c6.s2.6

The history of astronomy has, therefore, been divided into two major divisions, viz., (i) the Siddhāntic period and (ii) the pre-Siddhāntic period, and accordingly this book has been divided into two parts. ‘Part One’ gives the history of how the people in pre-Siddhāntic age had taken increasing interest in astronomy, how the relevant knowledge had grown, and how it reached the stage of foretelling the true places of planets, this history being traced from the casual astronomical references found in the Vedas, Vedāṅgas Smṛtis and the Mahābhārata, and the subsequent history up to the present time is given in ‘Part Two’. The pre-Siddhāntic period and consequently Part One, has again been sub-divided into two sections : (i) the Vedic period and (ii) the Vedāṅga period. The first section deals with the history of astronomy collected from references found in the Vedic Saṃhitās, Brāhmaṇic works and some Upaniṣads. The second section deals with the history of astronomy gleaned from the Vedāṅgas, the Smṛti works and the Mahābhārata. The Vedāṅgas contain two works whose whole subject matter is astronomy. These, however, deal with the mean motions and positions of planets and they are more ancient than the Siddhānta works, and that is why their study is given a place in Part One. A discussion of the limits of the periods to be assigned to the Vedic, the Vedāṅga and the Jyotiṣa-Siddhānta ages is given at the end of the part. ‘Part Two’ is devoted to the history of the three branches of astronomy.

v1.c6.s2.7

The history of mathematical astronomy in this part has been presented in the order of adhikāra or chapters, as already mentioned, viz., the mean motions, true motions, etc. A description of the celestial sphere, the system of observation, the precession of solstices, etc., have been given in the same part. In the treatment of these subjects references to several works and authors are required to be quoted, and without their knowledge some difficulty is likely to be experienced in rightly appreciating the discussion. Hence a detailed history of astronomical works and their authors is given in the chapter on the mean motions of planets in the beginning of ‘Part Two’ and a discussion of the mean places and motions of planets will be found in the same chapter. The chapter on the ‘true motions’ is devoted to the study of true positions, motions of planets and a detailed description of the five parts of the Pañcāṅga (almanac) and that of different Pañcāṅgas current in different provinces of our country.