What is the difference between a graha yoga (conjunction) and a yuga?
First, take a geo centric point of view. Then imagine that you are in the northern hemisphere. (Somewhere near Ujjain is better).
Then recognise that different celestial bodies are at different distances.
Know that the earth’s spin makes all celestial bodies appear to rise in the east and set in the west.
Know that the nakshatras always appear to to rise and set along the same celestial line or longitude. That is why they are called in general fixed stars.
Know that the Devas/Grahas – Surya (Sun), Chandra (Moon), Kuja (Mars), Budha (Mercury), Guru (Jupiter), Sukra (Venus), Sani (Saturn) do NOT rise and set along the same celestial line or longitude. The sunrise/other graha-rise position, is to the north or south relative to the previous day.
Observe that, there is a northen-most and a southern-most point for the sun/graha rises and sets.
Observe that all grahas have an uttaryanam when they tend north and on average and dakhsinayanam when the tend south on an average. Observe that some times a graha-rise can temporarily shift south during an uttarayanam and or shift west during a dakshinayanam. That is called a Vakra or a retrograde movement.
This entire effect is caused by
- the tilt of the earth’s axis to the orbital plane. The earth’s equatorial plane (the horizon as we observe it) is at 23.5 deg to the orbital plane. (The tilt increases as the earth slows down with age).
- a geo-centric view of the movements.. or observable movements.
Graha Yogas and Nakshatra Yugas : In their north-south movements, grahas can pass by each other.
The moon passes by every nakshatra and every other graha once a month.
- So a Chandra Nakshatra Yuga : for eg Chandra Dhanista Yuga occurs once a month.
- And a Chandra-Other Graha Yoga (Conjunction) eg Chandra Sukra Yoga also occurs once a month.
Surya passes by every every nakshatra and every other graha once a year. Therefore the Surya Nakshatra Yugas take place once a year and the Surya-Other Graha Yogas occur approximately once a year (not taking graha vakras into account).
- The Surya Chandra Yoga occurs every month and we know it as Amavasya or New Moon Day.
- One an average the Surya Sani Yoga occurs once in 30 years and the Guru Aditya(Sun) Yoga occurs once in 12 years. (Since the average geo-centric periods of Sani and Guru are 30 amd 12 years respectively).
- But for it to be a YUGA, a nakshatra must be involved. So a Guru, Aditya, Dhanishta Nakshatra alignment is called a Yugadi and the yuga duration is 12 years, the Kumbha Mela duration.
- The Surya, Chandra, Dhanishta Yuga is the Pitamaha yuga and it is 5 years long.
- The Surya, Chandra, Dhanishta, Sani Yuga is 30 years long. (Not used much).
- The Surya, Chandra, Dhanishta, Guru Yuga is the Barhaspatya Yuga and it is 60 years long.
- The Surya, Chandra, Dhanishta, Guru, Sani Yuga is also 60 years long.
Authorship and Copyright Notice : All Rights Reserved : Satya Sarada Kandula
Further Reading/ Future Reference/ I am yet to read it : http://ees2.geo.rpi.edu/geo2/Homework/HW1solar.pdf