27 Nakshatra
The Ancient Sages divided the zodiac(apart from twelve signs) into 27 Nakshatras or constellations of 13.20 degrees each. A Nakshatra is also called as lunar mansion or constellation. Its reference is found in the ancient Vedic scriptures. As per the Hindu mythology, all the twenty seven Nakshatras are the daughters of king Daksha and Moon is married to all of them and the Moon spends approximately one day each in one constellation and thus lunar month is of approximately of 27 days equal to the numbers of Nakshatras.
Nakshatras are classified as per several attributes like its owner, deity, sex, caste, species etc. The Nakshatra, in which one's Moon is placed at the time of birth, is called Janma Nakshatra or the birth star. These Nakshatras are further subdivided into four quarters known as Pada, each spanning 3.20 degrees, know as Navamsa. The placement of planets in these padas or subdivisions is studied for finer predictions. Each zodiac sign covers nine Padas in total. Thus we can see that Nakshatras are used for various purposes and one of its major uses is to determine starting point of a dasha or planetary period or cycles that divide the time in major periods and sub periods and to choosing a muhurtha or auspicious time for any important activity.