The twelf zodiacal signs are related to the Sun.
Nakshatras are closer related to the Moon.
The full power of Vedic astrology can only be achieved when both systems - Rasi and Nakshatra based - are used in combination.
27 or 28 Nakshatras
Most Nakshatra techniques are based upon a circle of 27 Nakshatras.
Nevertheless it is written that there are 28 Nakashatras, but the 28th (Abhijit) is hidden in Kali Yuga.
So methods that use the 28 Nakshatra system are supposed to be very old.
Most important of these is Sarvatobhadra.
Use Cases of Nakshatras
Birth Star is a popular name for the Moon's Nakshatra at the time of birth.
It is comparable to the zodiacal sign in popular western astrology (based upon the Sun's position).
Basic effects of the birth star are summarized on the Nakshatra Effects page.
Most important use case of Nakshatras are the Dasas (periods).
Dasas are important for the timing of events in the native's life.
Many Dasas are based upon the Moon's position in birth Nakshatra.
Most famous famous of them are Vimsottari, Yogini and Kalachakra Dasa.
Krishnamurti Paddhati (K.P.) is a system that uses the Vimsottari Dasa lords and sublords of the planets.
The K.P. system is quite famous among Vedic astrologers. It is one of the most successful systems for prediction.
Asta Koota is an analysis method for marriage compatibility.
It consists of eight elements. Some of them are based upon the birth Nakshatra
Rajju Koota is not part of traditional Asta Koota,
but another such element of Vedic partner astrology.
Sarvatobhadra is a technique based on the 28 Nakshatra system.
The Sarvatobhadra Chakra (SBC) is used to show the relationship of Nakshatras among
each other (Vedhas) and several other elements like weekdays or zodiacal signs.
Nakshatra Padas and Navamsa
A quarter part of a Nakshatra is called a Pada (i.e. foot).
Nakshatras have a span of 13°20', so a Pada is 3°20' - which is the span of Navamsa, too. Navamsa and Nakshatra Pada are the same.
Navamsa is the bridge between zodiac (Sun) and the stars (Moon).
This is a deeper reason why the Navamsa chart is so closely related to partnership and marriage.
Nakshatra Lords in Vimsottari Dasa
Each Nakshatra has a planetary lord used for Vimsottari Dasa and K.P. calculations.
The years assigned to the signs are the Mahadasa durations of Vimsottari Dasa.
Aswini, Magha, Moola
Bharani, Poorvaphalguni, Poorvashadha
Krittika, Uttaraphalguni, Uttarashadha
Rohini, Hasta, Sravana
Mrigasira, Chitra, Dhanista
Ardra, Swati, Satabhisha
Punarvasu, Visakha, Poorvabhadra
Pushyami, Anuradha, Uttarabhadra
Aslesha, Jyeshta, Revati
Special Nakshatras are counted from the birth star. These Nakshatras have special significations, e.g. on transits of other planets.