Hindu Astronomy
The Hindu Astronomy is one of the ancient astronomical systems of
the world. It is sometimes considered a controversial subject,
because some scholars argue that it shows a higher antiquity of the
Vedic culture as generally assumed.
Early cultures identified celestial objects with gods and spirits.
They related these objects (and their movements) to phenomena such
as rain, drought, seasons, and tides. It is generally believed that
the first "professional" astronomers were priests (Magi), and that
their understanding of the "heavens" was seen as "divine", hence
astronomy's ancient connection to what is now called astrology.
Ancient constructions with astronomical alienations (such as
Stonehenge) probably fulfilled both astronomical and religious
functions.
Calendars of the world have usually been set by the Sun and Moon
(measuring the day, month and year), and were of importance to
agricultural societies, in which the harvest depended on planting at
the correct time of year. The most common modern calendar is based
on the Roman calendar, which divided the year into twelve months of
alternating thirty and thirty-one days apiece. In 46 BC Julius
Caesar instigated calendar reform and created the leap year.
There are astronomical references of chronological significance in
the Vedas. Some Vedic notices mark the beginning of the year and
that of the vernal equinox in Orion - this was the case around 4500
BC. Fire altars, with astronomical basis, have been found in the
third millennium cities of India. The texts that describe their
designs are conservatively dated to the first millennium BC, but
their contents appear to be much older.
Yajnavalkya (perhaps 1800 BC) described the motions of the Sun and
the Moon in his book Shatapatha Brahmana, and also advanced a
95-year cycle to synchronize the motions of the Sun and the Moon.
The Vedanga Jyotisha, a text on Vedic astrology that has been dated
to 1350 BC, was written by Lagadha. It describes rules for tracking
the motions of the Sun and the Moon, and also develops the use of
geometry and trigonometry for astronomical uses.
The astronomy and the astrology of India are based upon sidereal
calculations. The sidereal astronomy is based upon the stars and the
sidereal period is the time that it takes the object to make one
full orbit around the Sun, relative to the stars. This is considered
to be an object's true orbital period. In Hindu Astronomy, the
vernal equinox (the First Point of Aries) is often calculated at 23°
from 0° Aries (1950 AD), i.e. about 7° Pisces. The constellation
that marks this vernal equinox is the Uttarabhadra. In the time of
the Puranas, the vernal equinox was marked by the Ashwini
constellation (beginning of Aries), which gives a date of about
300-500 AD. The Vishnu Purana (2.8.63) states that the equinoxes
occur when the Sun enters Aries and Libra, and that when the sun
enters Capricorn, his northern course (from winter to summer
solstice) commences, and the southern course when he enters Cancer.
In the Suryasiddhanta, the rate of precession at 54" (it actually is
50.3"), which is much more accurate than the number calculated by
the Greeks.
The Hindus use a system of 27 or 28 Nakshatras (lunar
constellations) to calculate a month. Each month can be divided into
30 lunar tithis (days). There are usually 360 or 366 days in a year.
The Hindu astronomer Varahamihira, Garga (quoted by Somakara), the
Mahabharata and the Vedanga Jyothish refer to the constellation
Dhanishta (Shravishta) and thus to an ancient calendar that would
have been used in 1280 BC.
The Kaushiktaki Brahmana and possibly the Atharva Veda refer to a
similar calendar.
The Atharva Veda, the Tandya Mahabrahmana and Laughakshi (quoted by
Somakara) may show knowledge of an earlier calendar, but still in
the Magha constellation. In still earlier Hindu calendars, the
vernal equinox was in the Krittika constellation.
There are additionally references to the summer solstice in the
Magha constellation.
This could indicate a date around 2000 BC. The Atharva Veda, the
Taittiriya Brahmana, the Shatapahta Brahmana, the Maitriyani
Upanishad and the Vishnu Purana show such a constellation in the
Krittika.
In the working out of horoscopes (called Janmakundali), the position
of the Navagrahas, nine planets plus Rahu and Ketu (mythical demons,
evil forces) was considered. The Janmakundali was a complex mixture
of science and dogma. But the concept was born out of astronomical
observations and perception based on astronomical phenomenon. In
ancient times personalities like Aryabhatta and Varahamihira were
associated with Indian astronomy.
It would be surprising for us to know today that this science had
advanced to such an extent in ancient India that ancient Indian
astronomers had recognized that stars are same as the sun, that the
sun is center of the universe (solar system) and that the
circumference of the Earth is 5,000 Yojanas. One Yojana being 7.2
kms., the ancient Indian estimates came close to the actual figure.
Brahmagupta (598-668) was the head of the astronomical observatory
at Ujjain and during his tenure there wrote a text on astronomy, the
Brahmasphutasiddhanta in 628. He was the earliest to use algebra to
solve astronomical problems. He also develops methods for
calculations of the motions and places of various planets, their
rising and setting, conjunctions, and the calculation of eclipses of
the Sun and the Moon. He said about gravity that "Bodies
fall towards the Earth as it is in the nature of the Earth to
attract bodies, just as it is in the nature of water to flow".
About a hundred years before Brahmagupta, another astronomer,
Varahamihira had claimed for the first time perhaps that there
should be a force which might be keeping bodies stuck to the Earth,
and also keeping heavenly bodies in their determined places. Thus
the concept of the existence of some attractive force that governs
the falling of objects to the Earth and their remaining stationary
after having once fallen; as also determining the positions which
heavenly bodies occupy, was recognized.
It was also recognized that this force is attractive force. The
Sanskrit term for gravity is Gurutvakarshan which is an amalgam of
Guru-tva-akarshan. Akarshan means to be attracted, thus the fact
that the character of this source was of attraction was also
recognized. This apart, it seems that the function of attracting
heavenly bodies was attributed to the sun. Brahmagupta estimated
in the 7th century that the circumference of the earth was 5000
yojanas. A yojana is around 7.2 kms. Calculating on this basis we
see that the estimate of 36,000 kms as the Earth's circumference
comes quite close to the actual circumference known today.
There is an old Sanskrit Sloka (couplet) which is as follows:
"Sarva Dishanaam, Suryaha, Suryaha, Suryaha."
This couplet means that there are suns in all directions. This
couplet which describes the night sky as full of suns, indicates
that in ancient times Indian astronomers had arrived at the
important discovery that the stars visible at night are similar to
the Sun visible during day time. In other words, it was recognized
that the sun is also a star, though the nearest one. This
understanding is demonstrated in another Sloka which says that when
one sun sinks below the horizon, a thousand suns take its place.
This apart, many Indian astronomers had formulated ideas about
gravity and gravitation.
The term Gurutvaakarshan can be interpreted to mean, 'to the
attracted by the Master". The sun was recognized by all ancient
people to be the source of light and warmth. Among the Aryans the
sun was defiled.
The sun (Surya) was one of the chief deities in the Vedas. He was
recognized as the source of light (Dinkara), source of warmth (Bhaskara).
In the Vedas he is also referred to as the source of all life, the
center of creation and the center of the spheres. The last statement
is suggestive of the sun being recognized as the centre of the
universe (solar system). The idea that the sun was looked upon as
the power that attracts heavenly bodies is supported by the virile
terms like Raghupati and Aditya used in referring to the sun.
While the male gender is applied to refer to the sun, the Earth (Prithivi,
Bhoomi, etc.) is generally referred to as a female. The literal
meaning of the term Gurutvakarshan also supports the recognition of
the heliocentric theory, as the term Guru corresponds with the male
gender, hence it could not have referred to the earth which was
always referred to as a female.
Many ancient Indian astronomers have also referred to the concept of
heliocentrism. Aryabhata has suggested it in his treatise
Aryabhattiya. Bhaskaracharya has also made references to it in his
Magnum Opus Siddhanta-Shiromani. But it has to be conceded that the
heliocentric theory of gravitation was also developed in ancient
times (i.e. around 500 B.C.) by Greek astronomers.
What supports the contention that it could have existed in India
before the Greek astronomers developed it, is that in Vedic
literature the Sun is referred to as the 'center of spheres' along
with the term Guru-tva-akarshan which seemingly refers to the sun.
The Vedas are dated around 3000 B.C. to 1000 B.C. Thus the
heliocentric idea could have existed in a rudimentary form in the
days of the Rig Veda and was refined further by astronomers of a
later age.
Indian Astronomers like Aryabhatta and Varahamihira who lived
between 476 and 587 A.D. made close approaches to the concept of
Heliocentrism. In the Surya-Siddhanta, an astronomical text dated
around 400 A.D., the following appellations have been given to the
sun. "He is denominated the golden wombed (Hiranyagarbha), the
blessed; as being the generator".
He is also referred to as "The supreme source of light (Jyoti) upon
the border of darkness - he revolves. bringing beings into being,
the creator of creatures". The Surya-Siddhanta also says that
"Bestowing upon him the scriptures (Vedas) as gifts and establishing
him within the egg as grandfather of all worlds, he himself then
revolves causing existence". Thus we can see that what ancient
Indian astronomers say comes close to the heliocentric theory of
gravitation, which was a thousand years later articulated by
Copernicus and Galileo inviting severe reactions from the clergy in
Rome.
Bhaskara (1114-1185) was the head of the astronomical observatory at
Ujjain, continuing the mathematical tradition of Brahmagupta. He
wrote the Siddhantasiromani which consists of two parts: Goladhyaya
(sphere) and Grahaganita (mathematics of the planets). He also
calculated the time taken for the Earth to orbit the sun to 9
decimal places.
Other important astronomers from India include Madhava, Nilakantha
Somayaji and Jyeshtadeva, who were members of the Kerala school of
astronomy and mathematics from the 14th century to the 16th century.
They were responsible for founding calculus and modern mathematical
analysis, along with a number of other developments.
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