SAMANTA CHANDRASEKHARA: THE PRACTICAL ASTRONOMER OF ODISHA
SAMANTA
CHANDRASEKHARA: THE PRACTICAL ASTRONOMER OF ODISHA
Nikunja Bihari Sahu
Samanta Chandrasekhara (1855-1904), a legendary
astronomer of Odisha who lived and worked in a purely Hindu orthodox style
during the British colonial period under the constraints of poverty and
hardship contributed significantly to the field of astronomy. He extended and
enriched the scope of Indian astronomy by virtue of his practical observations
of the night sky and corrected many anomalies in the existing astronomical and
astrological calculations. He is considered as the last link in the chain of India’s
long list of classical astronomers such as Aryabhatta-1 of Kusumapura (born in
476 A.D.), Varahamihira of Ujjaini (born in503 A.D.), Brahmagupta of Bhillamala
or Bhinmal in Rajasthan (born in 598 A.D.) and Bhaskara-II of Bijayapura or Bijapur in Karnataka (born in 1114 A.D.). Rather than being
dogmatic in his approach in accepting the results of the established astronomical
texts, he followed his own method of practical observation aided by his
ingenious instrumentation techniques in studying the night sky. He is often compared with Tycho Brahe
(1546-1601) for the striking similarity of his life and work with the Danish
astronomer of the sixteenth century known for his pre-telescopic observations
of the night sky.
Although the exact date of birth of Samanta
Chandrasekhara is debatable, he is believed to have been born on 13th
December 1835 in a royal family of the princely state of Khandaparagarh
presently in the district of Nayagarh. Struck with poverty, child
Chandrasekhara had little scope of receiving any systematic formal education or
access to the breathtaking developments of science which was sweeping the whole
western world at that time. There was no teacher who could instruct him in
depth in science and he was quite ignorant of any language other than Sanskrit
and his mother-tongue Oriya. Only a paltry collection of books in his family
library written on palm leaves in Sanskrit in purely classical style was the
sole source of information for him.
When he was just 10 years old, one of his
uncles taught him a little astrology and showed him few stars in the sky. This
aroused in him a curiousity for astronomy that lasted as a life-long
obsession. He kept on observing the
stars in the clear skies from his native place of Khandaparagarh which was
surrounded by the hills and jungles.
At
the age of 15 when he was able to calculate the lagnas (the zodiac sign rising
in the eastern horizon at the moment of one’s birth) and the ephemerides (a table or data giving the calculated positions of celestial objects at regular intervals throughout a period)
of planets, he was surprised to find
that neither did the stars appear on the horizon at the right moment, nor could
the planets be seen in their right places.
He was confused whether the ancient texts were fundamentally wrong in
their description of rules or his own way of observation was not accurate
enough as demanded by the merit of such task. Only correct measurement was
necessary to settle this doubt which essentially required the use of accurate
and precision instruments. As there was no instrument maker at that time in his
locality to supply him with the requisite tools to carry out such precise
measurements, young Chandrasekhara set out to develop his own armoury of
instruments out of whatever materials he found, such as bamboo or wooden
pieces. Sometimes, he used the shell of
the fruit Bottle gourd and iron bowl as the raw material to fabricate his
instruments. He constructed a number of instruments that could measure time,
angles in the sky, height of hills etc. He also developed some versatile instruments that could
measure multiple things with ease like both time and angles in terrestrial and
celestial conditions.
With these instruments, he achieved
astonishing accuracy in the measurement of celestial positions, eclipses and
planetary motions. While most of the instruments could not be found now, a
piece of his favourite device, called the Mana Yantra, is now preserved in the
Odisha State Museum, Bhubaneswar. He conceptualized an equatorial sundial in
line with the Chapa Yantra which was later put into form by his son Gadadhar
Sinha Samanta in 1905. Made of brass, the instrument now stands (in a
dilapidated condition) in the tahsil campus of Khandapara as a silent testimony
to the genius of Samanta Chandrasekhara.
At the age of 23, he started systematically
recording his observations on palm leaves. Three years later, he started
writing his results in Sanskrit shlokas and composed a masterpiece treatise
named Siddhānta Darpana, which was completed in 1869 when he was just 34. But
it took 30 years to get it published in Devnagari script from Kolkata. It
contains 2500 number of slokas of which 2284 were compiled by himself and the
rest were excerpted from the texts of other reputed scholars. This book contains
numerous instances of astronomical methods of determining the position and
motion of planets, mathematical treatment of spherical astronomy, corrections,
instrumentation techniques, improvements over earlier measurements, theories
and models.
Needless to say, the treatise served as a
standard source of reference for astronomers and astrologers in the state for
many generations. Even the treatise was adopted in the Lord Jagannath temple of
Puri for performing various rituals of the deities based on its computations.
Measurement
of Time
For any astronomical investigation, the first
thing that required to be measured precisely
was Time as it forms the basis of all calculations. As the mechanical clocks were much later
introduced by the Britishers, he built an array of his own time measuring
devices for his own use. He has described several instruments like Chakra
Yantra, Chapa yantra, Turiya yantra for
measuring time. While the Chakra yantra
was designed into a full circle, the Chapa yantra consists of half a circle and
the Turiya yantra looked one-fourth of a circle. He also frequently used the
Shanku yantra (or the Gnomon as the Greek called it) which was a vertical pole
that casts a shadow on the ground with the Sun in the sky. All these
instruments measure the Zenith Distance of the Sun from which the Time could be
easily calculated applying simple trigonometrical rules.
He has also given descriptions of several
water clocks or clepsydra namely the Ghatika yantra and the Swayambaha yantra
that could measure the time even without the sun. The Ghatika yantra consists
of an earthen pot with a hole at its base. It is floated in a tank of water.
Gradually, the pot gets filled up with water and sinks down which represented a
fixed time interval. Similarly, in the Swayambaha yantra, a bowl loaded
with some weight in the form of mercury,
was kept floating in a tall tank filled with water. It is connected to a
graduated wheel with the help of a cord. There is a fine hole at the base of
the tank through which water drips down steadily. The size of the hole was
adjusted in such a manner that it takes a full day to get all the water from
the tank emptied. With the descending water level, the bowl goes down continuously
pulling the cord that rotates the graduated disc. The time is ascertained by
reading the value with the help of a pointer.
Position
on the Earth globe
The next basic thing that was required for an
astronomical calculation was to measure the position of his own place on the
Earth’s globe. This requires the precise determination of his own latitude and
longitude. For measuring the latitude, he has given the rules on how the Shanku
yantra could be used. Its shadow length
cast by the Sun on an equinoctial day (the days when the durations of the day
and night are equal) at noon time (called Pallava) was measured from which the
Zenith distance of the Sun at that instant was determined. This Zenith distance
equals the Latitude of the place. Another method of finding the latitude was to
measure the altitude of the Pole Star. Samanta Chandrasekhara had the Mana
yantra in particular with him to smartly measure this value.
Model
of the Planetary system
The next thing that is important for an early
astronomer was to devise and follow a model of the planetary system on which he
would base all his calculations. Early Greek and Indian astronomers believed in
an Earth centric planetary system, i.e. the Earth was at the centre of the
system and all the planets including the Sun and the Moon were moving around
it. Our Hindu astronomers believed in the existence of nine planets or
Navagraha. Of them, the five naked eye planets like Mercury, Venus, Mars,
Jupiter and Saturn were certainly in the list. The Hindus also regarded the Sun
(Ravi) and the Moon (Chandra) as planets. The two nodes of the Moon (imaginary
points where the Moon’s orbit intersects the Ecliptic circle) called Rahu and
Ketu were also regarded as planets. Samanta’s model was a quasi-heliocentric system
and was a compromise between the
geocentric and heliocentric models.
According to this system, all the planets move around the Sun and the
Sun, carrying all the planets with it, moves around the Earth. The Moon, of
course, revolved around the Earth. The Earth was considered stationary and
centrally placed in this system. Hence, Samanta’s model of the planetary system
was more close to the helio-centric system (proposed by the Polish astronomer Copernicus
in the sixteenth century) than the model of preceding Hindu astronomers.
Surprisingly, his planetary orbits were not perfectly circular, but somewhat
oval shaped like the elliptical orbits proposed by the German astronomer
Johannes Kepler in the sixteenth century.
Measurement
of Planetary Parameters
The
Hindu astronomers were mainly interested in the position and motion of the
planets along the zodiac belt, (i.e. the ecliptic) because that played a key
role in astrology of preparing horoscopes of a new-born child and for predicting
the future. Samanta observed these nine plants in great detail along the
zodiac, calculated their mean motion per day, measured their revolution periods
and inclination to the ecliptic plane. As evident from the following tables,
his measurements happened to be more accurate than the results of his
predecessors and the more influential Bengali almanac of that time. He has
prescribed several corrections to be applied to the mean motion of the planets
so as to precisely determine their positions in the zodiac belt. The ephemerides
of planets computed from his elements were in close agreement with the Nautical
almanac followed in Europe at that time for navigation. While the Bengali
almanacs were in error by as much as 40 in angular measurements, the
corresponding error in Siddhanta Darpana was restricted to only half a degree!
A table showing the sidereal revolution
periods of the planets in days around the Sun is given below to gain an insight
into the accuracy of Samanta’s calculation over its predecessors:
|
Planet |
Surya
Siddhanta |
Siddhanta
Siromani |
Siddhanta
Darpana |
European
Value as in 1899 |
Modern
value |
|
Sun |
365.25875 |
365.25843 |
365.25875
|
365.25637
|
365.25636 |
|
Moon |
27.32167
|
27.32114
|
27.32167
|
27.32166
|
27.3216615 |
|
Mars |
686.9975 |
686.9979
|
686.9857
|
686.9794 |
686.97982 |
|
Mercury |
87.9585 |
87.9699 |
87.9701 |
87.9692 |
87.969256 |
|
Jupiter |
4332.3206 |
4332.2408 |
4332.6278 |
4332.5848 |
4332.589 |
|
Venus |
224.6985 |
224.9679 |
224.7023 |
224.7007 |
224.70080 |
|
Saturn |
10765.773 |
10765.8152 |
10759.7605 |
10759.2197 |
10759.23 |
|
Rahu
& Ketu |
6794.3948 |
6792.2535 |
6792.644 |
6793.270 |
6793.470 |
A
Table showing the inclination of the planetary orbits to the ecliptic plane is
given below:
|
Planets |
Surya Siddhanta |
Siddhanta Siromani |
Siddhanta Darpana |
European value as in 1899 |
Modern value |
|
Moon |
40 30’ |
40 30’ |
50 09’ |
50 08’48” |
50 08’33” |
|
Mars |
1030’ |
1050’ |
1051’ |
1051’2” |
1050’59” |
|
Mercury |
5055’ |
6055’ |
702’ |
7000’08” |
7000’18” |
|
Jupiter |
10 |
1016’ |
1018’ |
1018’41” |
1018’18” |
|
Venus |
2046’ |
306’ |
3023’
|
3053’35” |
3023’41” |
|
Saturn |
20 |
2040’ |
2029’ |
2029’40” |
2029’10” |
Predicting the Eclipses
The
eclipses played a great role in governing the daily rituals of the Hindu life
and, hence, predicting the eclipses were of paramount importance for an
astronomer. However, the actual occurrences of the eclipses did not agree to
the rules prescribed in the earlier texts due to several reasons. One of the
reasons was the adoption of an inaccurate value of the Parallax of the Sun and
the Moon in the eclipse computation. Parallax (it is the difference in
direction of an object seen by an observer from two widely separated places)
played a crucial value in forecasting the eclipses, as a slight change in its values
can alter an eclipse from partial to annular to total or vice versa. Samanta,
aided by his practical experiments, improved the values for the Parallax of the
Sun and the Moon and using these values, he improved the timings of the
eclipses. To determine the Parallax of the
Sun and the Moon, their respective distances from the Earth have to be
expressed in terms of Earth's radius. Not satisfied with the earlier values,
Samanta suggested an innovative experiment with the help of a coin so as to
determine the ratio of the Distance to the Diameter for the Sun and the Moon. A
table comparing the values for the Horizontal Parallax of the Sun and the Moon
as determined by various Indian astronomers is appended below:
|
Parallax of Objects |
Old Siddhantas |
Samanta Chandrasekhara |
Modern Value |
|
Sun |
3’ 56” |
22” |
8.9” |
|
Moon |
52’42” |
56’28” |
57’03” |
|
Difference of Parallax for the Sun
and the Moon |
48’46” |
56’6” |
56’51” |
Precession of the Equinoxes
The most puzzling question in astronomy
arises in expressing the longitudes of planets due to the constant shifting of
their reference points, i.e. the equinoxes along the celestial equator. These
are the two points where the ecliptic circle meets the celestial equator.
However, these are not fixed points, rather they keep on shifting westward due
to the precessional motion of the Earth’s axis. This creates an anomaly in the
measurement of longitudes of planets taken by different observers at different
times. While in our Indian system, the
measurement of longitudes begins from a fixed point called Meshadi, in the
Western system, it begins from the Vernal equinox (often called the First point
of Aries). However, this point is never fixed; it constantly shifts at the rate
of 50.27" annually and with it, the longitudes of the planets also change.
This phenomenon is known as ‘Precession of the Equinoxes’ (or ‘Ayana Calana’ in
our Indian system) and the amount of the angular measure of precession is
called the ‘Ayanamsha’.
A correct determination of the Ayanamsa
involves a number of factors like the rate of precession, the exact length of a
year, the year of the zero Ayanamsa and the star of reference. While various
astronomical texts have given the rate
of precession varying in a wide range from
45” to 60” a year, Samanta’s value was 57.615" per year. The modern
value of the precessional rate is, however 50.3" that differed markedly
from our Indian values. The discrepancy
in our Indian values may be explained from the fact that while the Indian
astronomers take the Sidereal year (the orbital period of planets around the
Sun taking the stars as a reference frame) as the base for calculation of the
rate of precession, the Western astronomers base their calculations on the
Tropical or Solar year (the time that the Sun takes to return to the same
position in the sky). Since the Sidereal year is longer than the Tropical year
by nearly 20 minutes, the Sun advances by an amount of 8.4" during this
time difference. When this correction is taken into consideration in the
calculation of Precession, Samanta's value turns out to be 49.179" in
close agreement with the modern value.
Samanta was an ardent observer throughout
his life. Barring few theoretical subjects, he had not recorded a single fact
without observation. He spent many sleepless nights under the starry sky to
record his observations. His magnum opus, the Siddhanta Darpana, presents these
findings in the form of traditional Siddhantic methods and meticulous
observations reaffirming the power of empirical science without Western
instruments.
Practical
observation, instrumentation techniques, physical measurements, improvisation
and innovation were the hallmarks of Samanta’s works. This made his results
more rational and reliable, making them popular in the society. Clearly, he
cast a formidable influence in Odiya life due to the acceptability of his
doctrine by people. His life and work will continue to inspire our young
generations to pursue a career in science and astronomy in days to come.
Further Reading
- An article in Oriya on “Calculation of Parallax for the
Sun and the Moon by Samanta Chandrasekhara”: Bigyana Diganta (May-June,
2004) by N.B.Sahu
- An article in Oriya on “Instruments of Samanta
Chandrasekhara”: Bigyana Diganta (Nov-Dec, 1997) by N.B.Sahu
- An article in
English on “Instruments of Pathani
Samanta” : Souvenir of 5th All India Amateur Astronomers Meet
‘Jyotiska’-1995 by N.B.Sahu
- An article in English
on “Popularising Classical Hindu Astronomical Instruments amongst
School Students”: Souvenir of 6th All India Amateur Astronomers
Meet-1996 by N.B.Sahu
- An article in Oriya on “Need for Introducing the
Instrument Shanku in Schools”:
Digbalaya, Orissa Physical Society, Vol-IV, Feb, 2002 by N.B.Sahu
- An article in Oriya on
“Mana Yantra of Samanta Chandrasekhara” :
Digbalaya, Orissa Physical Society, Vol-V, Feb, 2004 by N.B. Sahu
- An article entitled ‘The Enigma of Samanta
Chandrasekhara’ by Shri N. B. Sahu published in The Odisha Review, Dec 2024
issue
Education Officer
Regional Science Centre
Bhubaneswar
MANA YANTRA
GOLARDHA YANTRA
GOLA YANTRA
CHAPA YANTRA
CHAKRA YANTRA
SWAYAMBAHA YANTRA
Samanta's model of the planetary system
A brass equatorial sundial built by
Samanta Chandrasekhara’s son Gadadhar Sinha Samanta in 1905 and now kept in the
Tahsil office campus of Khandapara
Odisha Review Dec 2025 issue
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