Bearing in mind the 360 degrees of the elliptically structured zodiac, it can be divided into twelve houses with each house being equal to thirty degrees. With further subdivision of the same into twenty seven nakshatras or star constellation, each of the constellations occupies a magnitude of thirteen degrees and twenty minutes. Just as an individual takes birth under different rasis or zodiac signs governing the twelve houses, similarly the celestial presence of the twenty seven 'nakshatras' or birth star governs our birth. Lunar placement in natal or birth chart determines the birth star governing an individual.
Importance of Nakshatra
Since the constellation or nakshatra where moon finds its presence is known as the Janma Nakshatra and as moon influences the mental aspects of the native, nakshatra of the moon thus casts its indelible influence on moon. If one is born under Mars's nakshatra, it is likely to influence the aspects governed by Mars such as marriage and younger siblings. With each nakshatra having a planetary lord, the placement of the same (planetary lord) determines the initial dasa or 'phase' in the horoscope of a native. Nakshatra lords also play an important role in determining the essential quality of a person besides helping to assess the focal points of his energy and ambition.
With Vedic astrology giving much insistence on compatibility factors of bride & bridegroom, thorough matching of the horoscope prior to marital settlement is generally called for. Apart from taking into consideration the sun sign, rasi or moon sign, and the point of ascendance; nakshatra based compatibility is also emphasized. Nakshatra centric matching also known as 'koota- guna matching' helps to pin point the relative merit and demerits of the concerned pair in respect of one another. In the realm of Nakshatra matching at least eighteen positive points are necessitated for a union to be termed as compatible. As far as the similar matching is concerned, usually the cross checking follows from the girl's to that of the boy's with vertical calculation along the same row.