ASTRONOMY IN VEDANGA JYOTHISHYA

Time unit definitions(RVJ 16, RVJ17,YVJ24, YVJ30, YVJ38,YVJ39,RVJ9)

Measure of passage of time is very critical in relating natural phenomenon like Sun-Moon motion. Vedanga Jyotishya defines its own time units. It ranges from micro unit of about 0.1 second to macro unit of 5 solar year unit called Yuga. The units are Matra, Kashtha, kala, Nadika, muhurtha, paksha or Parva, masa, Ritu, Ayana, Varsha and Yuga. These time units are synchronized to angular sky observations of heavenly bodies. Evan our present day time-calibration has origins in time, angular position relation. The sun and moon angular positions along the ecliptic are calibrated with 27-unit Nakshatra system (VJ14). Vedanga Jyotishya also identifies equinoxes (Vishuvan), Solstices (Ayana) with reference to Nakshatras. The relations proposed in Vedanga Jyotishya are shown below.

10 Matra=Kashtha
124 Kashtha= 1 kala
10.05 kala= 1 Nadika
2 Nadika=Muhurtha (Muhurtha= about 48 minutes of present time)
30 Muhurtha= Day = 603 kala
366 days= Year=12 months= 6 ritus =2 Ayana
5 years= Yuga

Identity as Vedanga ( RVJ35)
Vedanga Jyotishya identifies itself as the vanguard of vedangas, clearly indicating that its synthesis was after all the Vedas were well established.

Peer evaluation and acceptance(YVJ2)
Vedanga Jyotishya text refers to peer evaluation and peer acceptance of the contents of the document. It calls itself the story of sun and moon, which has been accepted by all and by knowledgeable people (YVJ 42-43). Vedanga Jyotishya also identifies itself as providing ‘knowledge the time’ (RVJ 2). This demonstrates a high degree of academic evaluation for circa 1400 BC

Solar/lunar synchronization RVJ9,YVJ10
Nakshatra= 1/27th of the ecliptic
Thiti= Moon traverse time across one nakshatra or 13.3 deg of ecliptic
Parva (or paksha)= 180 deg of ecliptic sun-moon difference
Masa=full moon to full moon period
Ritu= 4.5 Nakshatra of sun motion (60 deg of ecliptic)
Ayana=3 Ritu (180 deg of ecliptic sun motion south or north)
Lagna= 1/27th of ecliptics

Nakshatra identity (RVJ25 through RVJ28,YVJ32through YVJ35)
The presiding deities of the 27 Nakshatras are provided. Note that Abhijit doe not figure in this list)