Astronomia Vedica - Part II

Cosmological Time Cycles in Indian Astronomy

Long before Copernicus, Galileo & Ptolemy, Aryabhata propounded the Heliocentric Theory of Gravitation, that all planets revolve around the Sun due to celestial gravity. The term given to Celestial Gravity was Guru-tva-Akarshana, which also has a philosophic meaning. Guru represents the Master, the Inner Sun, symbolic of the Self and the planets that revolve represent the students who are on their way to Self_Actualisation !

In Sanskrit Astronomy is known as Khagola Sasthra and Aryabhata worked at an astronomical observatory called Khagola. He studied at the University of Nalanda which housed more than 9 million books.

The Sexagesimal Division of a Day ( Sixtieth Division )

The Life span of Breath is 4 seconds, called as an Asu or a Pranakala in Sanskrit. 6 such Asus constitute a Vinadi and 60 such Vinadis constitute a Nadi. 60 Nadis is one day. In other words, a day is 86400 seconds and 21600 Asus. This sexagesimal division of a day is the base of Indian Astronomy. 15 such days constitute a Fortnight. There are two types of Fortnights - Dark Fortnight ( Krishna Paksha ) & Bright Fortnight ( Shukla Paksha ). These 2 fortnights constitute a month. Two months together is one Rithu and there are six seasons ( Rithus ). Aries & Taurus together is Vasantha, Gemini & Cancer Greeshma, Leo & Virgo Varsha , Libra & Scorpio Sharath, Sagittarius & Capricorn Hemantha and Aquarius & Pisces Sisira. Six months is one Ayana and there are 2 types of Ayanas - Dakshinayana ( the southern progress of the Sun, his declination South ) & Uttarayana ( the northern progress of the Sun, his declination north ). 12 such months or 6 Rithus or 2 Ayanas constitute a solar year. Since precession is 72 years per degree, one Age Cycle is 72*30 = 2160 years and 2 million Age Cycles is one Cosmological Cycle.

One Cosmological Cycle is 4.32 Billion years, known as a Brahma day. The Life span of Brahma is 100 sidereal years or 24.32360100 = 3.110410^14 years ! Indian Astronomy is graced by such gigantic calculations starting from 1/21600th of a day to 3.1104*10^14 years !

The Ursa Major Cycle

The constellation of Ursa Major ( The Saptha Rishies ) move backwards along the Zodiac, staying in a constellation for 100 years. To make a circuit of the Zodiac, they take 27*100 = 2700 years. This is known as an Ursa Major Cycle. Remarks Prof Drayson in "Asiatic Researches ", " The Indians thought proper to connect their mythology with an astronomical period of a strange nature. It is that of the Seven Rishies, moving along the Zodiac in a retrograde motion of 2700 years." Ursa Major was in Regulus at the start of the Mahabharatha War. The first astronomical calender was erected by the Indian emperor Vaivaswatha Manu ( circa 8736 BC ) and it was based on the Ursa Major Cycle.

D or Lunar Day ( Thidhi )

When we deduct the longitude of the Sun from the longitude of the Moon, we get the Thidhi or Lunation

D ( Lunar Day ) = Lm ( Longitude of Moon ) - Ls ( Longitude of Sun )

The First Lunar Day is called Prathama ( Moon within 12 degrees of the Sun ) , the Second is called Dwitheeya ( Moon within 12 and 24 degrees of the Sun ) and we have 14 lunar days before Full Moon. The 15th Lunar Day is Full Moon ( Pournami ). When the Moon is conjunct at 0 degrees from the Sun, it is New Moon ( Amavasya ). All Indian religious festivals are based on the position of the heavens.

Prathama Moon between 0 degrees and 12 degrees from the Sun

Dwithyeeya Moon between 12 degrees and 24 degrees

Thritheeya Moon between 24 degrees and 36 degrees

Chathurthi Moon between 36 degrees and 48 degrees

Panchami Moon between 48 degrees and 60 degrees

Shashti Moon between 60 degrees and 72 degrees

Sapthami Moon between 72 degrees and 84 degrees

Ashtami Moon between 84 degrees and 96 degrees

Navami Moon between 96 degrees and 108 degrees

Dasami Moon between 108 degrees and 120 degrees

Ekadasi Moon betw een 120 degrees and 132 degrees

Dwadasi Moon between 132 degrees and 144 degrees

Thrayodasi Moon between 144 degrees and 156 degrees

Chathurdasi Moon between 156 degrees and 168 degrees

Pournami Moon between 168 degrees and 180 degrees

East & West Points on the Celestial Horizon

East and West Points are two intersecting points between the Ecliptic and the Celestial Horizon. If on the Celestial Horizon, you mark E as East , W as West, N as North and S as South, then NES is the Eastern Celestial Horizon, SWN is the Western Celestial Horizon, ENW is the Northern Celestial Horizon & ESW is the Southern Celestial Horizon.

Ayana Sandhis - Intersecting Points between the Ecliptic and the Celestial Equator

The Ecliptic is slanted 23 degrees 27 minutes from the Celestial Equator. The intersecting points between them are called as Ayana Sandhis. These Sandhis are not static. They have a retrograde motion of 50.3 seconds per year. When the Sun crosses the Celestial Equator from the South to the North, that intersecting Point is Meshadi, the First Point of Aries and when he crosses the C E from North to South that point is called Thuladi, the First Point of Libra. At the start of the Dark Age ( Kali Yuga ), all planets were in the First Point of Aries. The First Point of Aries was in the constellation of Beta Arietis or Aswini. During the Vedic period, the First Point of Aries was in Karthika. That is why in the Vedas, the constellations are counted from Karthika onwards. Now Tropical Meshadi is behind Sidereal First Point of Aswini by 23 degrees 52 minutes. This motion of the Ayanas is called Precession.

A picture from the ' Five Astronomical Treatises " ( Pancha Siddhantika ) by Varaha Mihira showing a diagramatical picture of the calculation of eclipse.