ನಕ್ಷತ್ರ: ಚಂದ್ರನ ಮನೆ | Nakshatra: the moon’s lodging

The band of sky the moon travels through is divided into twenty-seven equal parts of 13 degrees 20 minutes each. Each is a nakshatra, and the moon occupies each one for roughly a day before moving to the next. The old word for them is chandra’s houses, the lodgings the moon rests in as it goes round.

The twenty-seven, in order from the fixed starting point: Ashwini, Bharani, Krittika, Rohini, Mrigashira, Ardra, Punarvasu, Pushya, Ashlesha, Magha, Purva Phalguni, Uttara Phalguni, Hasta, Chitra, Swati, Vishakha, Anuradha, Jyeshtha, Mula, Purva Ashadha, Uttara Ashadha, Shravana, Dhanishta, Shatabhisha, Purva Bhadrapada, Uttara Bhadrapada and Revati.

Each is associated with a group of actual stars. Rohini is Aldebaran, Chitra is Spica, Jyeshtha is Antares, Krittika is the Pleiades. The divisions are equal, though, so the boundaries no longer sit exactly on the stars they are named for.

Padas

Each nakshatra is quartered into four padas of 3 degrees 20 minutes. Twenty-seven times four gives 108, and those 108 quarters map neatly onto the twelve zodiac signs at nine padas each. The pada of your birth nakshatra determines the first syllable traditionally used in naming a child, which is why so many South Indian names begin with a syllable that is not the parents’ free choice.

Janma nakshatra

In much of South India the nakshatra the moon occupied at birth matters more than the sun sign. It is the janma nakshatra, and its return each month, roughly every 27.3 days, is observed by some families with a simple offering or a temple visit. Its return in the right month is the traditional birthday, kept before the Gregorian one.

It also governs practical matters: the nakshatra is consulted for travel, for beginning study, for a first haircut, and it carries weight in horoscope matching, where the nadi and gana attributed to each nakshatra are weighed.

How it is computed

Divide the moon’s sidereal longitude by 13 degrees 20 minutes. The whole number is the nakshatra, counting from Ashwini at zero. Sidereal means measured from a fixed point among the stars rather than from the moving equinox, which is why an ayanamsa has to be subtracted from the longitude an astronomer would quote. A nakshatra lasts about a day, but like the tithi its length varies with the moon’s speed, between roughly 20 and 27 hours.