Eternal India Encyclopedia

Eternal India encyclopedia

Ancient Concepts, Sciences & Systems

centre of learning. The famous university of Nalanda was located there. There was a special provision for the study of astronomy in the university. Aryabhatiya is the first earliest preserved work dealing with mathematics and planetary astronomy. Aryabhata came to the rescue of astronomy which did not have a scientific basis with the result that people's faith was badly shaken when there was a divergence between astronomical prediction and observation. Ar- yabhata reorganised astronomy on a scientific basis furnishing it with new tools and techniques and more accurate methods of observation. It was. generally believed that the earth was the centre of the universe round which the sun and the other planets moved. But Aryabhata differed from the other astronomers of the time in saying that the earth was not stationary but rotated about its own axis. For the sake of astronomical calculations, however, Aryabhata took the earth as fixed like the other astronomers did. That the earth was spherical in shape was well known. Apart from Aryabhatiya, Aryabhata wrote one more work on astronomy, Aryabhata-Siddhanta. Unlike the Aryabhatiya in which the day was measured from one sunrise to the next ( audayika ), the Aryabhata-Siddhanta measured the day from midnight to midnight (ardharatrika): This system was at the peak of its popularity in the 7th century when it was used in everyday calculations such as those pertaining to marriage, nativity etc. Brahmagupta (628 AD) brought out an abridged edition of the work under the title Kharida- Khadyaka ("Food Prepared with Sugarcandy"). It is in use even today in some parts of India. The ancient Indians were aware of the existence of only the seven planets ( graha) of the ancients : Sun ( Surya ), Moon ( Chan- dra ), Mercury ( Budha ), Venus ( Shukra ), Mars {Mangold), Jupiter (Brihaspati) and Saturn {Shani). To these, two more were added - Rahu and Ketu, the ascending and descending nodes of the moon - to formulate their Rahu-Ketu theories of eclipses. (The planets Uranus, Neptune and Pluto not observable by the naked eye came to be discovered during recent times and were not mentioned in the Hindu astronomical texts). The lengths of the year were known and calculated as also the lunar month. Eclipses were explained and accurately forecast. For nearly 2000 years, priestly astronomers saw eclipses as caused by Rahu (presumed to be the head of a demon) devouring the Sun or the Moon. It was Aryabhata who in the 5th century A.D. provided an explanation for the eclipses in terms of the Sun being obscured by the Moon and the shadow of the earth obscuring the Moon. Vara- hamihira explained clearly the cause of a lunar eclipse as being due to the entry of the Moon into the shadow of the earth. Nevertheless he preferred to use the Rahu terminology, stating that the ascend- ing node is Rahu's head while the descending node is Rahu's tail. Then, as now, religious rituals were observed during eclipses. Therefore great importance was placed on the accurate forecasting of eclipses. The astronomer, Parameswara (15th Century A.D.), observed and even recorded the lunar and solar eclipses which occurred over a period of 50 years. Because of their knowledge of mathematics, Indian astrono- mers made advances on the knowledge of the Greeks and passed their knowledge, along with that of mathematics, back to Europe through the Arabs. The Syrian astronomers (7th century) knew of

month was generally inserted after Shravana and called second Ashadha or Shravana. Thus every second or third year contains thirteen months. The natural means of measuring a year originated from the ex- perience of periodic recurrence of climatic seasons. Likewise, the natural means of measuring a day was the period between two con- secutive sun-rises and that for a month a period between two full- moons. The return of the Sun to the same position with respect to the fixed star might have appeared to be much more reliable than the slow seasonal variation of the length of day light. There appears to be a constant attempt at adjusting the lunar month with the season. The Taittiriya Samhita (7.2.6) mentions how 11 days ceremony ( ekadasharatra ) was performed after lunar year of 354 days to make up with the seasons ( ritus ) i.e. with the sidereal year of 365.25 days. The idea of intercalating a month at regular intervals of time or of adding 5 or 6 days in one month or more months was thus developed. The cyclic concept of time, developed from the idea of yuga or cycle, is a central feature of Indian astronomy. The Mahayuga is a period at the beginning of which all the planetary bodies are in conjunction. During the period they all perform integral (whole) number of revolutions and at the end of the period they are therefore again in conjunction. In the Surya-Siddhanta Mahayuga is divided into four mundane ages or yugas : the Krita or Golden Age, the Treta or Silver Age, the Dvapara or the Brazen Age and the Kali or the Iron Age (the current age through which the world is passing). The duration of these eras is 1,728,000, 1,296,000, 864,000 and 432,000 solar years respectively in the descending order of 4,3,2 and 1. The Kali Yuga began in 3102 B.C. A bigger period than a Mahayuga is a Kalpa which is equal to 1000 Mahayugas or 4,320,000,000 solar years. The length of a cycle was selected in such a way that the apsides and nodes also have whole numbers of revolutions. The Mahayuga of 4,320,000 years is such a period. The length of the solar year as 365 days 6 hrs 12 mins 35.56 secs is such that the least number of years containing a whole number of civil (solar) days is 1,080,000. (4X1,080,000 is 4,320,000). The number 108 is 4 times 27, the number of nakshatras. According to Aryabhata Ma- hayuga is divided into four equal parts of 1,080,000 years each. With the invasion of India by Alexander the Great in the 4th century B.C. and the subsequent Greco-Roman contacts the solar calendar and the seven-day week were also introduced. In the solar calendar the months are named after the signs of the zodiac, being translations of the Greek originals; Mesa (Aries), Vrishabha (Tau- rus), Mithuna (Gemini), Karkata (Cancer), Simha (Leo), Kanya (Virgo), Tula (Libro), Vrishcika (Scorpio), Dhanus (Sagittarius), Makara (Capricomus), Kumbha (Aquarius) and Mina (Pisces). The days of the week were named after their presiding planets as in the Greco-Roman system: Ravivara (Sunday), Somavara (Mon- day), Mangalavara (Tuesday), Budhavara (Wednesday), Brihas- pativara (Thursday), Shukravara (Friday) and Shanivara (Satur- day). Aryabhata occupies the first place among Indian mathemati- cians and astronomers of antiquity. He heralded the new science of mathematics-based astronomy. He was born in the 5th century A.D. in the reign of the Gupta king Buddhagupta and lived at Pataliputra (modern Patna) in ancient Magadha (Bihar) and wrote his Aryabhatiya there. Magadha in ancient times was a great Ashadha or