Tag Archives: Siddhantic astronomy

A universal history of astronomy as an educational aid


Rajesh Kochhar

Invited  talk delivered at XXVII General Assembly of International Astronomical Union  Special Session 4: Astronomy Education between Past and Future, Rio de Janeiro 6 August 2009

A man is wise with the wisdom of his age only,

and ignorant with its ignorance.    -Henry David Thoreau

History is an exercise in constructing the past carried out in the present with an eye on the future. Thus, paradoxical as it may seem , history converts the past into a bridge between the present and the future. As our perception of today and expectations from tomorrow change, our interpretation of yesterday must also accordingly change.

Human beings are an astronomical species. Ever since they learnt to walk upright they have looked at the sky and wondered. The sky has remained the same, but not its meaning. Astronomy is thus simultaneously a state-of-art intellectual enquiry as well as a symbol of the collectivity and continuity of humankind’s endeavours to come to terms with their cosmic environment. This collectivity can be conveniently discussed in terms of a three-phase model comprising (i) propitiatory phase; (ii) negotiatory phase; and (iii) the modern, curiosity-driven, impersonal phase.

To begin with, sky was home to divinities who were to be feared and appeased. As time progressed, human beings felt more secure and became intellectually more alert. Earlier awe made way for curiosity. Sky was now seen as a phenomenon which could be described The knowledge thus gained was employed to renegotiate the equation with celestial bodies. (iii) The third phase nominally began with Copernicus but took off with Galileo. Sky was now the abode of laws of nature which could be discovered and tested. Earlier astronomy had measured angles; now it could ascertain distances. The sky had acquired depth literally as well as figuratively. It is the transition from phase 2 to phase 3 which concerns us here.

Cultural Copernicanism

Post- world war II decades have ushered in an age which we may call the age of Cultural Copernicanism . In analogy with the cosmological principle that the universe has no preferred location or direction, principle of Cultural Copernicanism would assert that no cultural or geographical area or ethnic or social group can be deemed to constitute a superior entity or a benchmark for judging or evaluating others. This principle argues for a Trans-Cultural Civilizational Perspective whereby modern astronomy (or science in general) is seen not as a western brand but as the current phase of human cultural cumulus to which contributions at different times have come from different parts of the world.

This framework however is a recent development. Historiography developed in the long 19th century consciously projected modern science ( including modern astronomy) as a characteristic produce of western civilization, decoupled from and superior to its antecedents, with the implication that all material and ideological benefits arising from it ( and modern technology) were reserved for its authors.

As a reaction to this, the orientalized east has often tended to view modern astronomy as western astronomy , and sought to defend, protect and reinvent its “own” heritage. This defensive mindset works against the propagation of modern astronomy in many non-western countries.

It also warps their own accounts of their history. Those who act can retract, but those who react continue doing so.

Those to whom evil is done

Do evil in return. – W.H. Auden

If we wish to create enthusiasm for (modern) astronomy and teach it effectively, especially in geographical areas which have memories of their astronomical past, we must create links to the past and situate modern astronomy in a more extended evolutionary sequence.

Even for researchers, educators and students in astronomically advanced countries, a universal history of astronomy would be professionally beneficial and culturally satisfying. It will bring home the important lesson that at all times, including today, scientific breakthroughs have taken place only when inputs are received from diverse sources.

19th century historiography:Suggested correctives

There are two aspects to be considered: (A) How Europe constructed its own history of astronomy and (B) how it described earlier developments especially in India and the Muslim cultural zone (MCZ). (I am unable to say any thing about developments , e.g., in China.)

Greek science

My own assessment is that science in Europe would have developed exactly the way it did even if Greek science did not exist. This is because of the dynamism created by maritime voyages and the exorbitant profits therefrom. Europe however took its science’s roots back to ancient Greece. And stopped there. It refused to go into the antecedents of Greek science itself . Hellenic and Hellenistic periods were presented as a monolith so that by association Homer and Aristarchus would reinforce each other.

Greek science could arise only after Alexander. His conquests brought Greeks to the older civilizations of Egypt and Iraq, which had large surplus economies, vast geographical extent, higher levels of practical knowledge and technological advancements. These, when combined classical Greece’s intellectual prowess, gave rise to “Greek science”. But it did not suit Europe of the time to give any credit to Africa or Asia.

Terms like Hindu astronomy and Arab astronomy are isolationist and were intended as such. Moreover they are misleading. The word Hindu was not in use in 500 CE. And .as Ibn – Khaldoon pointed out , “ most Muslim scholars both in the religious and in the intellectual sciences have been non-Arabs”. Unfortunately, these terms continue to be used by sheer force of habit. They should be discarded in favour of purely descriptive terms like Siddhantic astronomy and Zij astronomy.

More generally, serious thought needs to be applied to the vocabulary employed. Words do not have any intrinsic meaning; they carry the meaning given to them. Some terms may appear innocuous to astronomers, but they may carry their own baggage from other area studies.

With reference to earlier epochs, terms like pre-scientific or ascientific astronomy have been employed even in serious literature. In contrast , ethno-astronomy or cultural astronomy may appear more acceptable , but they have their own shortcomings. They appear to be patronizing and an exercise in exoticism. ( All human activity including the modern scientific is cultural)

I have seen the use of term rational astronomy to refer to the modem phase. This seems to suggest that in earlier phases people made a distinction between the rational and the irrational and deliberately chose the irrational!

May be terms like solsticial (equinoctial) astronomy or colure astronomy or cardinal point astronomy can be used, because they are purely descriptive and not tainted by any association.

Incidentally, we routinely use geographical terms like India, China, and Egypt while discussing their antiquity. But an exception is made in case of Iraq which is invariably described in such difficult-to-comprehend terms like Mesopotamia, Babylonia, Chaldea, etc. This tends to decouple modern Iraq from its rich heritage. Why is this so?

Copernicus

Greek science was one of the big bangs for 19th century Euro-centric historiography; Copernicus was another. Some of the earlier accounts give the impression that he was not a product of his time at all , but was merely  taking sides in the  old dispute between Aristarchus’ heliocentrism and Ptolemy’s geocentrism.

Al-Tusi

The common use of a term like Arabic numerals raises the hackles of Indians who consider it to be a case of mis-branding. (This is true. ( Arabic/Persian call them Hind-se’, from India.) But terms like Arabic numerals and Algorithm, after Al-Khwarizmi, draw attention to an important historical fact , namely, arrival of intellectual inputs from MCZ into Europe.

What did Europe do with these inputs? More specifically, did they go into the making of Copernicus? Whether Al-Tusi deserves to be elevated from a lowly , early 19th century, footnote to the 21st century main text needs to engage the attention of present-day scholars, in a non-parochial context.

A universal history of astronomy would transcend patriotisms of all kinds.

Buddhists and Arabs

Arabs were  dismissively told that there role had been no more than as librarians and archivists for preserving  Greek science till Europe was in a position to take its heritage back. And yet, when Indians in their own context pointed out that in earlier times the Buddhists had  worked extensively  on health-related  chemistry , they were told with a straight face that  when their ancient texts mention Buddhist , they probably meant Arabs! Surely Arabs would have liked to hear that. But it was not considered necessary to inform them.

From about 500 CE till Kepler’s time , Indian astronomers were probably the only ones in the world who could calculate an eclipse with any reasonable accuracy. Disdainfully they were told that there was nothing original in their astronomy; it was a tame imitation of the Greeks. Indians did not retort that the only way to build an intellectual tradition is to absorb extant knowledge and build on it. Instead they weakly argued that the Greek borrowing was in astrology and not in astronomy, as if the distinction would have made any sense 2000 years ago.

Indians take pride in the appreciation earned by Indian texts in Baghdad, but are themselves less than liberal in acknowledging the role of Greco-Babylonian inputs around 1st century CE in revitalizing their Vedic astronomical tradition.

Since racial purity is an absolute no-no now , great emphasis is being placed on cultural purity. It is like discovering therapeutic virtues in distilled water.

Unlike the MCZ, Indian astronomical developments did not impinge Europe directly. The main concern of Siddhantic astronomers was the computation of planetary orbits. In the process they solved many equations which as formal mathematics caught Europe’s interest much later. Should they be the concern of only Indian historians?

History of astronomy functions at two levels. At one level we are interested in tracing the historical trajectory which leads to recent developments. But examination of high points that do not lie on the trajectory is also a legitimate field of enquiry. To put it attractively, if history has its compulsions, it also has its romances.

Thomas Godfrey’s 1730 invention of sextant in Philadelphia a year before Hadley invented it “ independently” the next year in England is an example of romance of history . Similarly European pre-history of telescope before Hans Lippershey’s commercial invention in 1608 is a fascinating subject. This line of enquiry should be extended to include similar episodes from other culture areas as well.

To sum up

Astronomy as a modern scientific discipline stands apart from most others in the sense that iy is collaborative rather than competitive. No person howsoever important, no nation howsoever powerful, no observatory howsoever well equipped is permitted a view of the whole celestial sphere.

It is a significant arrangement by nature that to know where you are located on the earth you must take the help of the sky ( stars/satellites).There is a rather obscure theorem in applied mathematics, known as Lichtenstein’s theorem, which tells you that for a rotating body like the earth the distinction between north and south along with the existence of equator is a mathematical fact , but the distinction between east and west is completely arbitrary.

We are all committed to the world-wide propagation of astronomical sciences. I have argued that to facilitate the task we must construct a universal history of astronomy so that every one feels they have contributed to it in the past and must do in the present and future as well.

Even otherwise an inclusive history is good for the world’s general wellness.

Aryabhata reinstalled


Rajesh Kochhar

Aryabhata (born AD 476) is the founder of Siddhantic astronomy which focused on developing mathematical algorithms for calculating planetary orbits and for predicting lunar and solar eclipses. His concise text, composed in AD 499 and known simply as Aryabhatiyam ( Aryabhata’s), influenced all subsequent work on the subject. From Aryabhata’s time till that of Kepler’s laws, Siddhantic astronomers were probably the only ones in the world who could calculate eclipses with any degree of accuracy.

Very little is known about Aryabhata himself. This is so because of the inherent limitations of the oral tradition. Astronomical texts were composed in terse metrical poetry, which was memorized and transmitted from one generation to the next by word of mouth. What was not considered worth preserving for the moment was lost for ever. It is thus not possible to construct a connected account of ancient astronomy or for that matter of any aspect of ancient India.

Internet has given birth to a flourishing industry of concocting details about Aryabhata and others and giving such details wide currency. By attributing to Aryabhata what he did not do , we would be belittling what he actually did.

Here is some authentic information on Aryabhata arranged in question- and- answer form.

Q1. What do we know about Aryabhata, the person?

A. First note that his name is spelt with a single t and not two. He was born in AD 476 and composed his work Aryabhatiyam in AD 499. This we learn from the book itself. The year of his death is not known.

Aryabhata says that he “ sets forth here the knowledge honoured at Kusumpura”. This has been interpreted to mean that Kusumpura was his work place. It has been identified with Patliputra which in turn has been equated with modern Patna.

This is all what we know about Aryabhata from him. Some additional information comes from his commentators ( e.g. the earliest, Bhaskara I ( AD 629)), who declared that Aryabhata hailed from a place , or district, called As’maka. It has not been possible to identify Asmaka. Legend prevails that Aryabhata hailed from Kerala. There is no basis for this. It is a well known fact that Aryabhata’s work was followed and improved upon in Kerala. Attempts to place Asmaka in Kerala may simply be manifestation of a desire to give physical basis to this intellectual relationship.

Bhaskara I also calls Aryabhata Kulapa. By a long shot this has been interpreted to mean that he was the vice-chancellor of Nalanda University! Kulapa could simply mean founder of a school, which Aryabhata certainly was.

The press coverage of 22 July 2009 total solar eclipse claimed that Aryabhata maintained an observatory at Taregna near Patna. This is an instance of history driven by tourism.

Inter-University Centre for Astronomy and Astrophysics, Pune, has erected a statue of Aryabhata to keep company with Galileo, Newton and Einstein. Bare-chested, stocky Aryabhata wearing a sacred thread is of course a figment of imagination. We have no way whatever of knowing what Aryabhata looked like.

Q2. Did Aryabhata believe in the spin of the earth?

A. He certainly did. But the whole thing should not be blown out of proportion.

We do not sense the spin of the earth under our feet. Instead the whole celestial sphere seems to be going around the earth. This indeed was the prevalent world view. Aryabhata boldly asserted that the earth was not static but spun on its axis.

He was severely criticized for this by friends and foes alike. His own follower Varahamihira died AD 587) believed that the earth was static. The otherwise brilliant mathematician astronomer Brahmagupta ( ) severely castigated Aryabhata for believing in the spin of the earth. Such was the onslaught of mainstream criticism that even followers of Aryabhata’s own school retreated. They rather ineffectually changed a word in the Aryabhatiyam text to argue that Aryabhata indeed considered the earth to be static.

If the scientific tradition had been based on written-down prose rather than on oral metrical poetry, Aryabhata’s reasons why he believed the earth spun would have been on record, and might have been considered convincing by later generations.

While today we give credit to Aryabhata for this, we should keep in mind that we know of Aryabhata’s belief in the spin of the earth not from his work or that of his followers but from the charge sheet maintained against him by his opponents. ( Just as we know about many nationalist heroes from the criminal complaint against them recorded by the colonial government.)

It is noteworthy that only a handful of later Indian astronomers believed that the earth rotated on its axis : Prthudaka (AD 860) and Makkibhatta ( AD 1377). Significantly , a religious text , Skandapurana (1.1.31.71) , following Aryabhata, describes the earth as a bhramarika ( spinning top).

It should be borne in mind that belief in spin of the earth or otherwise was not relevant for Siddhantic calculations. Brahmagupta did not believe in in it . But that does not mean that he was any the lesser astronomer. Aryabhata himself , like everybody else, maintained that the sun revolved around the earth. As far as kinematics is concerned it matters not who goes around whom.

Aryabhata believed that the earth was all water south of equator ( Gola 12) and that it expanded in size by one yojana during a day of Brahma and contracted during a night( Gola 8).

As Thoreau put it , “ A man is wise with the wisdom of his age only and ignorant with its ignorance”.

Q3. Did Aryabhata believe in heliocentrism?

A. As discussed above , no , he did not. WE take heliocentrism for granted. In its time, it had profound philosophical implications that went beyond planetary theory.Impact of heliocentrism on human thinking should not be under-estimated.

Q4. Did Aryabhata invent zero?

A. No, zero had been known long before that.

Q5.Is Aryabhata the founder of the eclipse theory?

A. No. He is probably the first one to apply it in India. Such theories were already known in Greece and China