the Ecliptic.
Nadis, Vinadis, Tatparas
An apparent Solar Day is 24 hours. According to Indian Astronomy, a solar day is 60 Nadis. 60 Vinadis is one Nadi ( Nazhika ) and 60 Tatparas is one Vinadi. There are minuter subdivisions like Pratatparas ( 60 Pratatparas constitute one Tatpara ), corresponding to micro seconds and nano seconds in Western time calculations. 2 and a half Nadis is one hour or 24 minutes is one Nadi.
While as per Western calculations, a day is reckoned from midnight to midnight, an Indian day is reckoned from sunrise to sunrise and a Hijra day is calculated from sunset to sunset.
Sidereal Solar Year
The time taken by the Sun ( from a geocentric perspective ), to make a circuit of the Sidereal Zodiac . This is 365 days, 6 hours 9 minutes and 9.8 seconds.
Tropical Solar Year
This is the time taken by the Sun to make a circuit of the Tropical Zodiac. This is 365 days 5 hours 48 minutes and 45.2 seconds. This is 20 minutes and 24.6 seconds less. This is because the First Point of Aries moves 50.3 seconds per year.
Sidereal Period of the Moon
The time taken by Luna to make a circuit of the Sidereal Zodiac. This is 27 days 7 hours 43 minutes 11.5 seconds.
Synodic Period
SP is the the time between 2 successive conjunctions. For the Moon, it is the time taken from New Moon to New Moon.
Solar Month & the Laws of Planetary Motion
SM is the time taken by the Sun to traverse one Sign. The motion of the Sun is fastest at Perigee ( near the earth ) and slowest at Apogee ( away from the Earth). ( This is the