Contributions of Indian Astronomers to the Advancement of World’s Civilisation

The Indian astronomer Aryabhatta calculated the rotation of the earth 1500 years ago with just a 0.009 second difference from today’s precise calculations, done with the latest scientific equipment. Even before that, in 800 B.C., Yagnavalkya not only suggested the heliocentric theory, but also calculated typical year as 365.24675 days. It is only 6 minutes longer than the accepted 365.24220 days, calculated using today’s modern instruments.

The Greek civilization is considered as the epitome of achievement by the Western Civilization; they believed that the Earth is flat and it is at the center of the universe.

During the same time in India, the ancient Indian astronomers already knew that the Earth was round; Sun was at the center of our solar system, and the Earth revolves round the Sun. Long time before Newton proposed his laws, they had a nascent idea of gravity being the force that makes the earth go around the sun, and the moon around the earth.

This achievement and its acceptance in Indian society would standout, considering the fact that beginning from Aristarchus (c. 310 – c. 230 BCE) to Copernicus (1473-1543), every conclusion supported the concept of Heliocentrism i.e., Sun is the center of the solar system. Also, the same was supported by Galileo in 1633.

Cleanthes (c. 331 – c. 232 BC), a Greek philosopher, had objected to the concept of Aristarchus, with his religious vehemence to the teachings of Zeno, and stressed the belief that the universe is a living entity and that God is the invigorating force of the universe. Similarly, Martin Luther (1483-1546), a religious leader, voiced his disapproval to this heliocentric solar system model of Copernicus, whose theory on Heliocentrism was published just before his death in 1543 as De revolutionibus orbium coelestium. Andreas Osiander, a subordinate and minister of Martin Luther, pronounced against Copernicus, “This fool wants to turn the whole art of astronomy upside down.”

While Indian civilization accepted the heliocentric model in 8th Century B.C., the Western Civilization did not accept till the 18th century. Those who are aware of the achievements in the field of Astronomy by the Ancient Indians are filled with wonder at the achievements, and the acceptance in our society of such advances, which were nearly two thousand years ahead of other important civilizations existing at that time.  

Ancient Indian astronomers had significantly contributed towards the advancements in the field of astronomy, and the above is just an example of it. In this article let’s look at the contributions of Indian astronomers to the advancement of world’s civilization.

The Siddhanthic Era of Indian astronomy

Started around 1300 BC, this period has observed new concepts of astronomy diverging from vedic literature. The early Siddhanthic era began with a series of books called the Siddhanthas (solutions) and we can find three great Indian astronomers during this period – Lagadha (1350 BC), Yajnavalkya (900-800 BC), and Aitareya Brahmana (900-800 BC). Let us see the inventions and assumptions during this period.

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  The astronomer, Aitareya Brahmana mentioned in his test that the Sun never sets, nor rises, which indicates that the Sun is stationary.

• Yagnavalkya found that the Earth was round and supported the heliocentric theory as mentioned in the Vedas.

• In his astronomical text, Shatapatha Brahmana, Yagnavalkya also mentioned that ‘the sun strings these world – the earth, the planets, the atmosphere – to himself on the thread,’ which indicates that earth and other planets revolve round the sun in orbits.

• He also recognized that the Sun is much larger than the Earth and accurately measured the relative distances of the Sun and the Moon from the Earth as 108 times the diameters of these bodies, almost close to the modern values obtained using latest instruments of 107.6 for the Sun and 110.6 for the Moon.

• Yagnavalkya also proposed a 95-year cycle and determined the average length of the tropical year as 365.24675 days, which only 6 minutes longer than the modern value of 365.24220 days.

• Other texts from this period also mentioned that Sun is in all the directions and it is just like the other stars in the universe, but is much nearer than the rest.

These are all the contributions to the Indian astronomy during the early Siddhanthic era, in fact, the most prominent inventions happened during the real Siddhanthic era.

The Golden Era of Indian Astronomy

The real Siddhanthic era which was almost entirely recorded began in the 5th century. Aryabhatta is a remarkable contributor of this era who adopted a rigorous mathematical approach to the astronomy. He wrote one of his most famous works, Aryabhatiya, during this period. Few other contributors are Varahamihira, Brahmagupta, Bhaskara II. Below are their contributions to the Indian astronomy.

Aryabhatta – The golden contributor

Born in the year 476 AD., Aryabhatta’s birth place is always debated. Many say that he belongs to the region lying between the rivers of Narmada and Godavari, which was called as Asmaka country. Some commentators recognize the Asmaka country with modern Maharastra. However, the place at which he wrote his excellent work Aryabhatiya in 499 A.D., is definite as Kusumapura or Pataliputra, which is modern Patna. Pataliputra was under the king Buddha Gupta, the last ruler of Gupta empire, also known as golden period of India.

Contributions of Aryabhatta to Indian astronomy

• Earth besides revolving round the Sun also rotates on its own axis.

• Light for the moon and the other planets including earth is reflected from the Sun.

• Planets revolve round the sun in elliptical orbits and he propounded an eccentric elliptical model of planets, from which he accurately calculated some astronomical constants.

• Calculated various astronomical concepts such as the time of occurrences of solar and lunar eclipse, motion of the moon (expressed as a differential equation), number of rotations of the earth, etc.

• He also proposed the theory of earth’s rotation which laid undiscovered until the European Renaissance and Copernicus.

• The mathematical concepts of forecasting ellipses given by Aryabatta gave the Europeans some methods of measuring the volume of spheres and the area of triangles.

• Aryabhatta stated that 1,582,237,500 rotations of the Earth equal 57,753,336 lunar orbits. This is an extremely accurate ratio of a fundamental astronomical ratio (1,582,237,500/57,753,336 = 27.3964693572), and is perhaps the oldest astronomical constant calculated to such accuracy.

The exceptional job of Aryabatta’s followers

Varahamihira (505 AD) – Newton of ancient astronomy

• Found that the same force which is holding objects to the Earth also held the celestial bodies in place.
• Also noticed that there must be some type of attractive force which keeps objects stationary on the earth.
• His inventions were advanced upon Anaximander’s idea of equilibrium and a recognition of a photo-gravitational theory, long before Newton.

Brahmagupta (598 AD)

• Understood that the earth is spherical and calculated the circumference of the earth to be 36,000 kilometers which is very close to the actual figure.
• He re-emphasized Aryabhatta’s idea that another day starts at midnight.

Bhaskara II (1114 AD)

• Bhaskara’s ‘Sidhantha Siromani’ is the last great works of Indian astronomy.

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  Bhaskara expanded Aryabhatta’s heliocentric model in Sidhantha Siromani.

• Also found that planets run with different velocities and calculated solar and lunar eclipses.

Later other astronomers like Sripati (1045 AD), Mahendra suri(14th century), Somayaji (1444 AD) etc. also contributed other concepts of astronomy.

The Ancient Hindu Calender – First and the most accurate:

One more great contributions from the same period in which the Indian astronomy flourished is the ancient Hindu calendar, which till date have lot of relevance and accuracy. However, it has undergone many changes in the process of regionalisation.

A general overview of the Hindu Luni-Solar calendar is as follows.

• The year consisted of 12 lunar months of different names ranging from Chitram to Phalgunam.
• Each Lunar month is of 29 ½ days.
• One month divided into Suklapaksha (bright days) and krishnapaksha(dark halves).
• The day was adopted as Thithi.
• A group of 2 months form a season – Vasantha, grishma, varsha, sarad, hemantha, and sisira.
• Since 12 lunar months make only 354 days, for every 30 months an extra month is added.

Instrumental science

Astronomers of that period do not have any technically advanced equipment, but they still managed to built their own crude equipment with which they arrive at near perfect measurements of astronomical movements. Few of the astronomical instruments are as follows

• The Gnomon (Sanku) – the vertical part of the sundial whose shadow is used to indicate the hour of the day.

• The Cross staff (Yasti Yantra) – a tool used to measure the angle between the directions of two stars.

• The Clepsydra (Ghati Yantra) – a tool used to measure time.

• Armillary sphere (Gola Yantra) – is a model of objects in the sky, a smooth sphere, whose principal purpose is to map the constellations.

• Phalaka-yantra – a rectangular board with a pin and index arm, used to determine time from the sun’s altitude.

• Equatorial sundial (Kapala Yantra) – used to determine sun’s angular measurement in a spherical coordinate system.

The scientific temperament of ancient Indian astronomers

• Looking at the achievements of our ancient Indian astronomers, we can clearly understand the advancement of science in that period.

• The inventions and observations of the astronomers show their in-depth knowledge, strong hold on the subject, and their never ending thirst for knowledge.

• Aryabhatta wrote his excellent works Arybhatiya and Arya-siddhatha (treatises on Mathematics and Astronomy), at the age of 23. This shows his hard work and commitment at a very young age and also implies that there is someone ahead of him who was able to guide and direct him properly.

• Rejecting the superstitions which are rooted firmly in the society shows the confidence and an aim to educate the society with the facts.

• A detailed study on astronomy and an appraisal of the observation methodology and attitude of the astronomers reveals their strong scientific basis.

• Constructing and using unique tools to study the astronomical movements shows their expertise.

• We can also find out-of-the-box thinking like moving in divergent directions and involving variety of aspects (mathematics, astronomy, physics) to get novel solutions, which later became excellent works of the period.

Earlier Indian Astronomy from Vedas

The early signs of Astronomy in India were found in the Rig Veda and the Atharva Veda, dated 2000 B.C. During this period the astronomers used to observe movements of stars and planets to device astronomical charts and many other cosmological theories. The following are the assumptions mentioned in the Vedas

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  The universe is too old and it’s evolution and decline are cyclic.

• Both the Vedas point to the observance of a lunar year and the Moon itself was regarded as the maker of months (Masakartha).

• According to Vedic idea year is of 366 days. And in every 5 years, one month is omitted to maintain 12 months of 30 days in a year.

• The earliest concept of heliocentric concept (discussed in the introduction of the article) is found in many Vedic texts.