GENIUS OF INDIA - ECLIPSE AND INDIAN ASTRONOMY

Tonight, 25th April 2013 - today is an important day for if anyone looks at the night sky they would be witnessing a wonder of nature. The Lunar Eclipse - popularly known as 'Chandra Grahanam' in India.
The fantastic cosmic event that generates curiosity for the learned, fear for the religious and 'just another day' for an ordinary folk.
This post is my humble beginning to discuss the views on the Lunar Eclipse - 'Chandra Grahanam'.
One of my friend in Facebook commented once that our Indian knowledge is so vast but not much has surfaced. This post is an attempt at giving more understanding to what 'Grahanam' is from an Indian prospective and how valid it is to today's science.

CHANDRA AND SURYA GRAHANAM

Grahanam is the Indian word for Eclipse. Chandra Grahanam and Surya Grahanam are Lunar and Solar Eclipse in Indian terminology.
The cosmic event is closely followed up by the traditional indian calendar ( almanac ) maker.
The calculations they give are outstanding and accurate to the minutes and seconds of the time of eclipse.
The way they calculate this is using the 'Indian Sidereal calendar system' also known as 'Sayan Calendar'.
This is an extremely brilliant science that was developed far back as 5000 years ( note - Astrology with the nodal calculations features prominently in Mahabharata ) or still way back.
These detailed calculations show the achievements in terms of Mathematics, observations in astronomy and a sound knowledge of cosmology.
Apart from the superstitions surrounding this cosmic event, the Indian Almanac was a curious book that kindled my imagination and curiosity.
I have detailed below some of my understanding of this great science of Astronomy from the Indian way. Hope this will be a good read and if you find it interesting, please do drop your comments.
I have many questions of my own on many of the basic as well as advanced concepts in this field and I am still a student - so, please feel free to correct me through your comments.
Constructive criticisms is most welcomed - abusers - please excuse.

RAHU AND KETU IN GRAHANAM

There is this popular myth and superstition surrounding snakes, Rahu and Ketu.
The duo Rahu and Ketu do not feature in Vedic literature and neither during the Ramayana period.
They feature more prominently in the end of Mahabharatha and in the puranic times.
One reason might be scientifically, the moon was so close to earth during the Ramayana period and later moved farther from earth during the Mahabharata and Puranic times.
This view is based on the recent findings that the moon is getting farther away from earth every year ata rate equivalent to the rate of nail growth on human finger per day.
But there are some deeper meanings for their linkage to snakes - which are a separate topic which I would try to write later.
In Puranas, the Rahu and Ketu duo were first the part of a single demon, who cheated the devas and got the nectar of immortality. As a punishment, Lord Vishnu cut off the demon into two and created Rahu and Ketu.
They got snake parts to compensate for their limbs and vowed to swallow the Sun and Moon, who blew the cover, during the eclipse.
Religion apart - the Rahu and Ketu as per serious Indian Astronomy, are actually the cutting points of the Moon's orbit and the orbit of earth around sun.
This is well explained by the image below.

People wrongly assume that Indian Astrology and Astronomy considered a Geocentric universe ( one in which earth is the center of universe and sun and moon went round it ), while it is not so.
The way the Indians charted the sky is to look from earth. In that view, one is considering the motion of other planets and stars around the earth. Hence they charted the path of sun - while the sun was stationary, the path was actually that of earth's elliptical orbit around sun. So, when they mean 'Path of Sun' - what they are actually trying to chart is the elliptical path of Earth which is tilted at an angle around the Sun. This was proved by Aryabhatta in his famous river rowing experiment.

Now comes the curious part - According to Indian Astrology - which is closely related to Astronomy -

the shadows Rahu and Ketu move in anti-clockwise direction while all the planets move in clockwise direction in the Indian Astrological Rasi Chakra.
This is a great finding - this describes the idea of optics that was developed in India.
We all know that the shadow grows in opposite direction to the direction of light.

A lunar eclipse or Chandra Grahanam occurs when the shadow (Rahu) is on the Moon, while the Sun is in the straight line with earth.

This is shown by the diagrams below.

So, when such a shadow falls on the moon, the moon appears to go through a dark phase and immediately appears after the passage through the nodes.

So, an Indian Astronomer - needs only to look at the Almanac and check when the alignment with the nodes Rahu and Ketu with the Moon and Sun takes place and he could predict the date of eclipse.
The exact time depends on the stars - nakshatras - through which the nodes are present and through which the Moon is passing.
The accurate time of passing of Moon against the star is known and hence, an Indian Astronomer can put a detailed calculation on when the 'Grahanam' or the eclipse will occur.
These details have been done well documented by great Indian Astronomers - like Aryabhatta  (476–550 CE), Varahamihira (505–587 CE) and Brahmagupta (597–668 CE), which was close to 1400 years before the west understood that the earth was round and took several centuries to come out with these detailed calculations.

ASTROLOGY - ASTRONOMY AND SCIENTIFIC THINKING

Indian Astrology chart (South Indian format) for today and how the planets would appear in the space

Astrology and Astronomy in India are for much of the time intermingled.
Indians believed in practical purpose for Astronomy.
Even though today's world considers Astronomy as a science and Astrology as a mombo - jumbo religious b.s., Indian Astrology is much to do with the following:
1) The Indian Almanac or Panchanga - which is again used in Astrology is the one used for Agriculture.
2) The Almanac plays important part in predicting rains for the coming year using calculations based on several factors like position of planets, stars, transit of moon, etc.,
Science today states the moon and sun produces waves due to 'Gravitational pull'.

So, the Almanac predictions on cloud formation ( I will write another interesting topic I found on this by Varahamihira), are mostly based on the gravitational pull that's exerted by Moon and Sun when earth goes through different sides of its elliptical orbit. There are several other factors like gravitational pull of bigger outer planets and smaller inner planets. All these are taken into consideration.

The human body and much of animals, plants and almost all living beings have water as an integral part of their system.

So, one can very well understand what might be happening to our body water with all those combined gravitational forces acting. Indian Astrology just tires to map these behaviors ( I will write in detail on this in another post ).
GREAT CONTRIBUTORS TO ASTRONOMY

I think I have given much in this post to ponder upon.
How are we to know these things from history - are there records?? - Yes there are - these are not the sayings or musings of Indians, but well documented by foreign astronomers and travelers like

Hsüan-tsang

Fa Hien

Al-Biruni 

All these foreigners have been awe-struck and documented 'THE GENIUS OF INDIA'.
Just before finishing, I wish to pay my tributes to the great Indian Astronomers who, with the support of the rulers and scientific apparatus, were able to map the cosmos and planted the seed of science in the Indian arena.

Aryabhatta

who is one of my icons of Indian genius - Gave the book 'Aryabattiyam' - the standard book of Indian Astronomy

Varahamihira

An Astronomer par excellence - his 'Brahat Jatakam' and 'Brahat Samhita' are filled with such great astronomical findings.

Brahmagupta

Today the world knows Indian Numerals and Astronomy, thanks to his, 'Brahmasputasiddhantham'.

And also to the Grand Astronomical Observatories built by them,

Their efforts did not come by some 'mombo-jumbo' magics - they have been developed by detailed calculations they made and the algorithmic models they developed to finally arrive at the standard conclusion.
They painstakingly verify and correct every year using the shadows falling at the various scientific apparatus in places like Jantar Mantar at Delhi, Jaipur, etc.,
The west has denied their contributions for long - just because they got the calculations done in easy way by observing the shadows from the earth and noticing the movement of planets by bare eyes.

MESSAGE TO FUTURE

It was the kings like Bhoja Raja and Maha Raja Jai Sing II ( of Delhi Jantar Mantar fame ), that astronomy and other sciences developed in India.
If at all the Government of India wishes to encourage and make a 'BRAND INDIA', it has to again start up and fund universities of grand education like the ones at Nalanda to teach this traditional knowledge.
For common folks like us, we must encourage ourselves and our little ones to 'WATCH THE SKIES' - by taking them to Planetariums, Observatories or at the least buying a telescope.

So, tonight, at 1:15 a.m, when you see the Lunar Eclipse, don't fail to see both the beauty of the cosmic cycle as well as the Indian Genius that mapped this show several thousand years ago.
India and Indians need such scientific temper - to know the unknown - for so says the Vedas -

'Asatho maa Satga Maya - Thamaso maa Jyothirga Maya' - Lead me from falsehood to Truth - from darkness of ignorance to light of knowledge.