Aspects of Indian History for Engineers

Module IV- Scientific Achievements in

Ancient India

Astronomy in ancient India

INTRODUCTION:

Astronomy first appeared in the Indian subcontinent during the Indus Valley civilization in the third millennium BCE, when
it was used to create calendars. Because the Indus Valley civilization did not leave written records, the Vedanga Jyotisha,
which dates from the Vedic period, is the oldest extant Indian astronomical text. The 4th and 6th centuries AD are considered
the "Golden Age of India" because India made enormous advances in mathematics, astronomy, sculpture, and painting
during this time period.

Astronomy During Ancient times - Features

•Astronomy has made great strides. Planetary motion was emphasised and closely monitored. The Jyotishvedanga texts
established systematic categories in astronomy, but Aryabhatta dealt with the more fundamental issue.
•His Aryabhattiya is a short text of 121 verses. It includes sections on astronomical definitions, methods for determining the
true position of the planets, the movement of the sun and moon, and the calculation of eclipses.
•The earth was a sphere that rotated on its axis, and when the earth's shadow fell on the moon, it caused a Lunar eclipse, and
when the moon's shadow fell on the earth, it caused a Solar eclipse.
•The orthodox theory, on the other hand, explained it as a process in which the demon swallowed the
planet. Varahamihira described all of these observations in Panch Siddhantika, which summarises the five schools of
astronomy prevalent at the time.
•Aryabhatta deviated from Vedic astronomy and gave it a scientific perspective, which later astronomers followed.
•In ancient India, astrology and horoscopes were studied. Aryabhatta's theories marked a significant departure from
astrology, which emphasised beliefs over scientific explorations.
Astronomy In Vedas

The Samhitas are texts that contain hymns, charms, invocations, and sacrificial formulas. They are derived from the
four Vedas.
 The Rig Veda (the Book of Devotional Verse)
 The Yajur Veda (the Book of Sacrificial Formulae)
 The Sama Veda (the Book of Chants)
 The Atharva Veda (the Book of Mysticotherapeutic Priestcraft)
Their emergence follows a lengthy oral transmission period following their organisation in the four Samhitas.
The Rig Veda and Atharva Veda songs make reference to the lunar calendar's maintenance. The Moon was
historically regarded as the "month-maker" (maakrt).
Cont.
Numerous indicators of autumn equinox awareness exist, all of which are connected to:
 Aditi (which corresponds to Pollux, longitude 113°)
 Daksha (Vega, longitude 284 degrees)
 Rudra (Betelgeuse, longitude 88 degrees)
 Rohini (Aedebaran, 69 degrees of longitude).
The shifting longitudes are caused by the precession of the equinoxes. These details aid in
determining the composition dates of the works.
The Yajur and Atharva Vedas exhibit a distinct calendrical awareness; several sacrifices, such as the Gavam
Ayana, are of varying durations to correspond to the Sun's daily cycle.
The day was divided into three, four, five, or fifteen equal divisions for ceremonial purposes, each with its own
distinct name.
Apart from the twenty-seven stars that begin with Krttika, these Vedas mention five planets and give two of
them specific names: Jupiter (Brihaspati) and Venus (Vena).
Indian Astronomy and Vedas

•The Rigveda (c1700-1100 BCE), one of Hinduism's primary and foremost texts, contains the first records of sophisticated
astronomy in India dating back to at least 2000 BCE.
•The ancient Indian astronomers used the stars and planets to create astrological charts and read omens, developing sophisticated
mathematical models and many intriguing theories, many of which were passed down to the Islamic world and Europe.
•According to the Rigveda, the Indians divided the year into 360 days, which were then divided into 12 months of 30 days.
•Two intercalary periods were added every 5 years to bring the calendar back in line with the solar year, ensuring that years
averaged 366 days.
•The Indian year, however, migrated four days every five years, and Indian astronomers constantly tweaked and adjusted their
calendars over millennia.
•The text also demonstrates that the Indians used four cardinal points to ensure that altars were properly oriented.
•The Jyotisa Vedanga, the first Vedic text to mention astronomical data, records events as far back as 4000 BCE, though many
archaeo astronomers believe it may include observations as far back as 11 000 BCE.
•They note that some of the records may have been copied from earlier manuscripts, but more research is needed in this area
because many of the references are unclear and couched in religious terminology.
•Many advances in measuring time and the progression of the heavens occurred during this period, as well as a few proto-
theories about the structure of the universe.
•More importantly, this time period witnessed the exchange of ideas between Indians, Babylonians, Greeks, and Persians. This
exchange of theories and philosophy was critical to the advancement of astronomy.
Jain Literature:
The Ardha-Magadhi Prakrit writings are comprised of fragments and oral traditions drawn from the Punva Jain scriptures. This
recasting was undertaken by the Svetambara sect, resulting in the publication of 45 or 50 volumes. Following are the fundamental
texts:
Angas
These are connected to rituals, legends, and doctrines. Sthananga and Bhagavatisutra are two of the angas that deal with
astronomy and mathematics, respectively.
Other sutras include Acaranga, Sutrakrtanga, Samavayanga, Jnatrdharmakatha, Upasakadasa, Antakrtadasa, Anuttera-aupapa-
tikadasa, Prasna-Vyakarana, Vipakasutra, and Drstivada.
Upangas
These are also twelve in number, with Suryaprajnapati, Candraprajnapati, and the seventh part of Jamudvipaprajnapati all
devoted to astronomy.
The second section of Jambudvipaprajnapati is devoted to the study of time, from asankhyata ('incomprehensible minuscule
time') to sirsaprahelika, or millions of years.
Prakirnakas
Eleven essays are linked together in this collection.
Chedasutras
These nine volumes contain both monastic and civil law.
Cont.
Mulasutras

Certain mathematical and astronomical truths are contained in the first of the four
Mulasutras—Uttaradhyayana, Avasyaka, Dasavaikalika, and Pinda-inryukti.

The Culikasutra is a two-part treatise on astronomy and mathematics. It is divided into two
sections: Nandisutra and Anuyogadvarasutra.

The Jain response literature is represented by works such as Umasvati's (185-219 A.D.)
Tattvarthadhigama Sutra on astronomy and cosmology, Yati Vrsabha's (473-609 A.D.) 7000-
verse Trilokaprajnapati, Chapter 27 of which is devoted to astronomy, and Padaliptacharya's
(based on the Suryaprajna Pad
The Universe's Geographical Center
Mount Meru was regarded as the axis of the Earth's centre, while the latter was regarded as a stationary planet. These two
elements, along with stars, planets, continents, rivers, oceans, and mountains, are from Jambudvipa (lit. "rose-apple country").

Mount Meru represents the primordial inner essence that gives birth to everything (or reality) and has a spiritual significance.

Mount Meru is depicted in the centre of Jain literature's cosmic images, with the twelve months, planetary cycles, and the
motions of the sun and moon depicted on the outermost boundary.

The Polar Star is depicted directly above Mount Meru in this illustration.

The Siddhantas: Source of Astronomical Knowledge

From the eighteen early siddhantas composed by Pitamaha, Surya, Vyasa, Atri, Vasistha, Kasyapa, Parasara, Narada, Garga, Manu,
Marici, Lomasa (Romaka), Angiras, Bhrgu, Paulisa, Cyavana, and Yavana, only five passages have survived.

Surya's, Vasistha's, Pitamaha's, Paulisa's, and Romaka's siddhantas are included in Varahamihira's Panchasiddhanta (578 A.D.).

Later siddhantas reflected significant advancements in astronomy; they were far more precise, and calculations were far more
precise and straightforward than before.
Indian Astronomy and the Siddhantic Era
•During this time, a new branch of astronomy emerged that diverged from the Vedas. The Siddhantic
Era began with the Siddhanat, or 'Solutions,' a series of books that charted the solar year, including
solstices, equinoxes, lunar periods, solar and lunar eclipses, and planetary movements.
•The Siddhantic Era saw three great Indian astronomers, who are sadly little known in the west despite
their significant contributions.
•At a time when the Greeks were still using celestial crystal spheres to explain the cosmos, Indian
astronomers proposed that the stars were exactly like the sun but much further away by the first
century CE.
•They also recognised that the earth was spherical, and Indian astronomers attempted to calculate the
planet's circumference.
Astronomy During Shunga Empire
•During the Shunga Empire, astronomy advanced, and many star catalogues were created. The Shunga period is
known as India's "Golden Age of Astronomy."
•It saw the development of calculations for various planets' motions and positions, their rising and setting,
conjunctions, and eclipse calculations.
•By the sixth century, Indian astronomers believed that comets were celestial bodies that reappeared on a regular
basis.
•This was the view expressed by the astronomers Varahamihira and Bhadrabahu in the sixth century, and the
10th-century astronomer Bhattotpala listed the names and estimated periods of certain comets, but it is unclear
how these figures were calculated or how accurate they were.
Aryabhata
•Aryabhatta, who was born in Kerala and lived from 476 AD to 550 AD, graduated from the
ancient university of Nalanda.
•He then moved to Bihar, where he continued his education at a renowned learning institution
nearby Kusumapura.
•He spent the late 5th and early 6th centuries living in Taregna District in Bihar.
•Aryabhatta was a mathematician, astronomer, astrologer, and physicist who lived in the fifth
century.
•He was also a mathematician who broke new ground.
•Aryabhatta was a famous mathematician during the Gupta period. He authored Aryabhattiya at
the age of 23 and afterwards Arya-Siddhanta.
•He worked on a pi estimate of 3.1416.
•In trigonometry, he discovered that the area of a triangle equals the product of a perpendicular and
the half-side.
•He also observed the movements of the solar system and calculated that the solar year
lasts 365.8586805 days.
•Aryabhatta stayed in Kusumpur, Pataliputra.
•The Aryabhatiya cites Aryabhata being 23 years old 3,600 years into the Kali Yuga, however this
does not imply that the work was written at that period.
•This year corresponds to 499 CE, implying that he was born in 476.
•CONT.
•He wrote Aryabhattiya, a compendium of mathematics at the period. It is divided into four pieces.
•He presents the approach of indicating large decimal values using alphabets in the first part.
•The second half contains challenging problems from current Mathematics areas such as number theory, geometry,
trigonometry, and algebra.
•Zero and Aryabhatta: He demonstrated that zero was more than simply a number; it was both a symbol and a
notion.
•He calculated the precise distance between the Earth and the Moon.
•The discovery of zero introduced a new dimension to negative numbers.
•The final two parts of Aryabhatiya are on astronomy, also known as Khagol-shastra (Khagol was the famous
astronomical observatory at Nalanda, where Aryabhatta studied).
•It was necessary for the advancement of the science of astronomy to have accurate calendars, a better
understanding of climate and rainfall patterns for timely sowing and crop selection, fixing the dates of seasons and
festivals, navigation, time calculation, and casting horoscopes for use in astrology.
•Because of the need to traverse oceans and deserts at night, knowledge of astronomy, particularly knowledge of
the tides and stars, was crucial in commerce.
•He rejected the belief that our world is 'Achala' (immovable) and asserted that 'the earth is spherical and spins on
its own axis.'
•Using examples, he demonstrated that the appearance of the sun travelling from east to west is incorrect.
•One example is when a person goes by boat, the trees on the coast appear to move in the other direction.
•He also claimed that the moon and planets are illuminated by reflected sunlight, which was eventually proven in
contemporary times.
Contributions to Astronomy
•He also provided a scientific explanation for the solar and lunar eclipses, dispelling the
myth that the eclipses were caused by Rahu, Ketu, or another rakshasa (demon).
•As a result, India's first satellite into orbit was christened Aryabhatta.
•In several sources, he appears to relate the apparent motions of the sky to the rotation of
the Earth.
•He could have imagined the planets' orbits were elliptical rather than circular.
•Contrary to widespread belief at the time, Aryabhata accurately stated that the world
revolves on its axis on a regular basis and that the apparent movement of the stars is caused
by the rotation of the globe.
•This is alluded to in the first chapter of the Aryabhatiya, where he specifies the number of
earth rotations in a yuga, and is discussed in the gola chapter.
•According to Aryabhata's geocentric conception of the solar system, the Sun and Moon are
each carried by epicycles.
•Solar and lunar eclipses were scientifically described by Aryabhata.
•Aryabhatta explored the actual cause of solar eclipses in the Surya Siddhanta.
•Reflecting sunlight, he claims, illuminates the Moon and planets.
•CONT.
•He explains eclipses as shadows thrown by and falling on Earth, as opposed to the commonly held belief
that eclipses are caused by Rahu and Ketu (identified as the pseudo-planetary lunar nodes).
•He describes the size and extent of the Earth's shadow in considerable detail (verses gola.38–48), and then
explains how to compute the size of the obscured section during an eclipse.
•Heliocentrism: As previously stated, Aryabhata pushed for an astronomical model in which the Earth
rotated on its own axis.
•His model also corrected the speeds of the planets in the sky in terms of the Sun's mean speed.
•Thus, it has been proposed that Aryabhata's calculations were based on a heliocentric model in which the
planets orbit the Sun, albeit this has been refuted.
•Aryabhatta gave the irrational value of pi. He deduced ? = 62832/20000 = 3.1416 claiming, that it was an
approximation.
•He was the first mathematician to give the 'table of the sines', which is in the form of a single rhyming
stanza, where each syllable stands for increments at intervals of 225 minutes of arc or 3 degrees 45'.
Alphabetic code has been used by him to define a set of increments.
WORKS

Aryabhata is the author of several treatises on mathematics and astronomy ,some of which are lost.
His major work, Aryabhatiya, a compendium of mathematics and astronomy, was extensively
referred to in the Indian mathematical literature and has survived to modern times. The
mathematical part of the Aryabhata covers arithmetic, algebra,pla ne trigonometry, and spherical
trigonometry. It also contains continued fractions, quadratic equations, sums-of-power series, and a
table of sines.

The Arya-siddhanta:
The Arya-siddhanta, a lot work on astronomical computations, is known through the writings of
Aryabhata's contemporary, Varahamihira, and later mathematicians and commentators, including
Brahmagupta and Bhaskara I. This work appears to be based on the older Surya Siddhanta and uses
the midnight-day reckoning, as opposed to sunrise in Aryabhatiya. It also contained a description of
several astronomical instruments: the gnomon (shanku-yantra), a shadow instrument (chhAyA-
yantra), possibly angle-measuring devices, semicircular and circular (dhanuryantra / chakra-yantra), a
cylindrical stick yastiyantra, an umbrella-shaped device called the chhatra-yantra, and water clocks of
at least two types, bow-shaped and cylindrical. A third text, which may have survived in the Arabic
translation, is Al ntf or Alnanf. It claims that it is a translation by Aryabhata, but the Sanskrit name of
this work is not known. Probably dating from the 9th century, it is mentioned by the Persian scholar
and chronicler of India,Abū Rayhān alBīrūnī
Varahamihira
•Varahamihira (c. 505 - c. 587) was a Ujjain-based ancient Indian astrologer, astronomer, and polymath (Madhya
Pradesh, India).
•The Brihat Samhita, an encyclopedic work on architecture, temples, planetary motions, eclipses, timekeeping,
astrology, seasons, cloud formation, rainfall, agriculture, mathematics, gemology, perfumes, and many other topics, was
one of Varahamihira's most notable works.
•Indian astronomers proposed in the sixth century that the same force that held objects to the Earth also held the
celestial bodies in place.
•Long before Newton, this was an advancement on Anaximander's concept of equilibrium and recognition of a proto-
gravitational theory.
•Varahamihira proposed that objects must be held stationary by an attractive force.

•Books

Brihat Samhita
•The Brihat Samhita, an exhaustive study on architecture, temples, planetary motions, eclipses, timekeeping,
astrology, seasons, cloud formation, rainfall, agriculture, mathematics, gemology, fragrances, and many other
themes, was one of Varahamihira's most famous works.
•Varahamihira claims that while he summarised prior works on astronomy, the Shilpa Sastra, and temple building in
some lines, his exposition of many design ideas and models is among the earliest texts that have survived.
•Al Biruni, a Persian traveller and scholar, cited passages from the Brihat Samhita and lines from Varahamihira.
Surya Siddhanta
Surya Siddhanta
•In India, astronomy equipment had been used prior to 1000 BC. The "Surya Siddhanta," a well-known
book for astronomical computations, was composed around this time.
•The name ‘Suryasidhanta' means ‘sun theory,' and it relates to the observations of star and planet
positions.
•Later, some Indian mathematicians created their own tools and techniques to aid in the comprehension
of the "Surya Siddhanta" theory.
•The introduction of zero to mathematics and the decimal system of calculating are two such priceless
contributions.
•In his four other panchasiddhantika treatises, Paitamaha Siddhantas, Paulisha Siddhantas, Romaka
Siddhantas, and Vasishta Siddhantas, Varahamihira contrasted Surya Siddhanta with them.
•Aryabhata also makes reference to the Surya Siddhanta in his writings.

Pancha Siddhanta
•Suryasidhanta was one of the five astronomical theories that were in use before the time of Christ, and
Varahamihira did a fantastic job of compiling them.
•This group of texts is referred to as the "Panchasiddhantika."
•He had created a wide range of string and ring instruments.
•It is a compilation of both Hellenistic and Vedanga Jyotisha astronomy.
•The equinox shifts by 50.32 arc seconds annually, according to Varahamihira, who was the
Other Contributions of Varahamira:
•Varahamihira also made several significant discoveries in the fields of hydrology, geology, and
ecology.
•His claim that termites and plants can sense subsurface water is increasingly receiving support
among scientists.
•Additionally, he wrote a lot. His command of Sanskrit language and poetic rhythm allowed him
to express himself in a distinctive manner.
•He became well-known due to his encyclopaedic knowledge and engaging presentation of even
the most boring subjects, including astronomy.
•He has been promoted to the same level of astrology as Kautilya, Manu, and Panini in political
philosophy, law, and grammar thanks to his works like the Pancha Siddhantika (Five
Principles), Brihatsamhita (Master Collection), and Brahjataka (Astrological study).
Bhaskara II
•Bhaskara II (1114-1185) was the head of the astronomical observatory in Ujjain, carrying on
Brahmagupta's mathematical tradition.
•He composed the Siddhantasiromani, which is divided into two parts: Goladhyaya (sphere)
and Grahaganita (mathematics of the planets).
•He also calculated to 9 decimal places the time it takes the Earth to orbit the Sun. At the time,
the Buddhist University of Nalanda offered formal courses in astronomy.