Indian Calendar

 INDIAN CALENDAR

Elements of the Indian Calendar

• Coordinate system

                      

The ecliptic plane is the plane that contains the orbit of the Earth around the Sun

The sun is said to be in a nakshatra or Rasi if the line joining the Earth with Sun goes through that nakshatra (star) or rasi (constellation)

The celestial sphere is an imaginary sphere centered on the Earth used to measure the positions of the stars  through angles Azimuth and Altitude

The moon and almost all the planets are found within a belt of width 8 degrees on either side of the ecliptic plane, and this belt is known as the Zodiac or the Rasichakra

Solar and Lunar Years

• Solar year (Samvatsara) is the time taken by the Earth to complete one revolution around the Sun. That means, after exactly one solar year, the Sun will return to the same star (background of stars). It is equal to 365.2564 days.
• Lunar year (AnuVatsara) is 12 cycles of Full Moon to Full Moon (or New Moon to New Moon). It is equal to 354.3671 days. 
  

Thus, there is a discrepancy of 10.9 days in the Solar and Lunar years. After every Five years the Sun and the Moon come to the same position in the background of stars. This 5-year cycle is used to synchronize the solar and Lunar calendars by adding two Lunar months (Adhika masas).

Five components of Panchanga: These five components uniquely 

• Tithi
• Nakshatra
• Vara
• Karana
• Yoga
  

The Sun moves at the rate of 1 degree per day, with respect to the Earth. The Moon moves at the rate of 13 degrees with respect to the Earth. The difference between the longitudinal positions of the Sun and the Moon is Tithi

The Moon is in the green color longitude (i.e. the line joining centres of Earth and Moon in this longitude). The Sun is in blue color Longitude. The Integer part of the angle between these two longitudes is called TITHI.

The Nakshatra, at any instant, refers to the particular portion of the ecliptic in which the moon is situated. In the above picture, the moon is situated in Nakshatra #3 i.e., Krittika

There are 27 Nakshatras (lunar mansions) in Vedic astrology. They are: 1. Ashvini, 2. Bharani, 3. Krittika, 4. Rohini, 5. Mrigashirsha, 6. Ardra, 7. Punarvasu, 8. Pushya, 9. Ashlesha, 10.Magha, 11.Purva Phalguni, 12.Uttara Phalguni, 13.Hasta, 14. Chitra, 15.Swati, 16.Vishakha, 17. Anuradha, 18. Jyeshtha, 19. Mula, 20. Purva Ashadha, 21. Uttara Ashadha, 22. Shravana, 23. Dhanishtha, 24. Shatabhisha, 25. Purva Bhadrapada, 26.Uttara Bhadrapada, and 27. Revati