Ancient Indian Astronomy
Hindu calendar
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Brahma lives 100 years (Brahman years, not
human years)
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One Kalpa coincides with one Day of Brahma’s life.
One Kalpa corresponds to 4,320,000,000 earthly
years.
Earthly time is divided into Yuga, or Ages
which are:
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Krita ( or Satya ) Yuga
Treta-Yuga
Dwapara-Yuga
Kali-Yuga
4,800 years
3,600 years
2,400 years
1,200 years
Calendar
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For a total of 12,000 years.
The four Yuga make one Mahayuga
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The 12,000 years must be multiplied by
360, the days of the human year
12,000 x 360 = 4,320,000 years
Every Kalpa has 1000 cycles of four
Yuga
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4,320,000 x 1000 = 4,320,000,000 years
Astronomers
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Varahamihira (~500CE)
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described the Earth as spherical and as
being suspended in space
Used latitude and longitude
Described the stars as “fixed” and gave the
planets a constant speed.
Astronomers
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Aryabhata I (~500CE)
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Heliocentric (somewhat) idea
1000 years before Copernicus and Galileo
Described methods of eclipse prediction.
Codified many trigonometric laws.
Sin tables
Value of pi
Knew of most of the planets (at least 7)
without a telescope
Astronomers
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Brahmagupta (~600CE)
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Estimated the Earth’s circumference as
5000 yojanas (yojana = 4.5 miles)
Surprisingly accurate! (off by less than
10%)
Devacharya (~600CE)
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First astronomer to describe a method for
calculating the precession of the eqinoxes
The Planets
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Hindu astronomers used epicycles (like Ptolemy) to
describe the motion of the planets in a geocentric
solar system.
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Aditya – the Sun
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Epicycles are necessary to account for retrograde motion.
Son of Aditi (the unchangeable)
Soma – the Moon
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Peace, gentleness
The Planets
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Budha – Mercury
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Shukra – Venus
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Burning coal
Brihaspati – Jupiter
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Refined, sensual
Ankgaraka – Mars
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Intellect
Great protector
Shani – Saturn
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Slow
Interesting Notes
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Hindu texts speak of Pravaha, a celestial
wind, the force that moves the planets.
There is a famous Sanskrit saying when
translated means, “In all directions, Sun, Sun,
Sun.”
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Seems to be suggesting that all the stars are suns,
just further away
Olbers’ paradox long before Olbers!
Invasion!
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With the invasion of the Moghuls,
astronomy in India did not advance for
some time.
Think of what might have been
achieved
Controversy
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Throughout history some scholars have
been determined to prove that these
ideas and theories could not have
originated in India
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19th century notion that India did not have
observational astronomy.
Controversy
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More than 30 years ago, Roger Billard
analyzed ancient calculations which were to
predict the position of planets
Compared to modern theory, they were
surprisingly accurate!
Aryabhata’s constants are more accurate than
the West’s at that time
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Not this advanced in Babylonia
Cannot be from Babylonia!