Constellation is a group of stars, shining in the sky. There are countless stars in the sky and Bha – Chakra, which make some particular shapes, like – horse, shakat, snake, hand, chakra, triangle etc. Indian astrologers seem to have named various constellations on the basis of their shapes, like Ashwini, Bharani, Krittika etc. Sun is also a similar shining star. Just like Sun, all the constellations emit their own light. They do not receive light from any other star, as the Moon, Mars or other planets do.
As the distance between two places on earth is expressed in k.m. or miles, the distance of Sun, Mars and other planets is expressed by constellations. Ancient books tell about countless constellations. According to Skanda Purana, the number of constellations is eighty samudra, fourteen arab and twenty crore. This includes some famous constellations like Saptarshi Mandal, Mareechi, Vashishtha, Angira, Atri, Dhruwa, Agastya etc.
According to Atharva Samhita and other ancient books as well as modern Astronomers, there are 88 constellations on both sides of the Kranti Vritta in the Rashi Path Bha Chakra 9 degree south.
Indian astrologers have selected 27 or 28 constellations out of these 88 main constellations.
The sun, the moon, the mars and all the planets keep on coming under influence of all these 27/28 constellations of the Bha – Chakra, and exert influence accordingly. Indian astrologers have mathematically accepted the 27 constellations falling under Kranti Vritta and the Bha-Chakra. The 28th Abhijit constellation is less used generally, being 61 degree 44 minutes away from the Kranti Vritta.
Just like Kranti Vritta, the Bha – Chakra also has 360 degrees in the sky. Dividing by 27 constellations, each constellation gets a value of 13 degrees 20 minutes. Remember, lunar constellations are given special importance in Indian Astrology, because Moon is the master of the Mind, and being nearest to earth, it has special influence on the child in the mother’s womb.