Ancient Indian Astronomy

Hindu calendar Brahma lives 100 years (Brahman years,

not human years) 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: Krita ( or Satya ) Yuga 4,800 years Treta-Yuga 3,600 years Dwapara-Yuga 2,400 years Kali-Yuga 1,200 years

Calendar For a total of 12,000 years. The four Yuga make one Mahayuga

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 4,320,000 x 1000 = 4,320,000,000

years

Astronomers

Varahamihira (~500CE) 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 Aryabhata I (~500CE)

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

Brahmagupta (~600CE) Estimated the Earth’s circumference as

5000 yojanas (yojana = 4.5 miles) Surprisingly accurate! (off by less than 10%)

Devacharya (~600CE) First astronomer to describe a method

for calculating the precession of the eqinoxes

The Planets Hindu astronomers used epicycles (like

Ptolemy) to describe the motion of the planets in a geocentric solar system.

Epicycles are necessary to account for retrograde motion.

Aditya – the Sun Son of Aditi (the unchangeable)

Soma – the Moon Peace, gentleness

The Planets Budha – Mercury

Intellect Shukra – Venus

Refined, sensual Ankgaraka – Mars

Burning coal Brihaspati – Jupiter

Great protector Shani – Saturn

Slow

Interesting Notes 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.” Seems to be suggesting that all the stars are

suns, just further away Olbers’ paradox long before Olbers!

Invasion!

With the invasion of the Moghuls, astronomy in India did not advance for some time.

Think of what might have been achieved

Controversy

Throughout history some scholars have been determined to prove that these ideas and theories could not have originated in India 19th century notion that India did not

have observational astronomy.

Controversy 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 Not this advanced in Babylonia Cannot be from Babylonia!