The 27 nakshatras: a sky map older than the zodiac

The Moon's stations

The Moon completes a circuit of the stars in about 27.3 days. Divide its path into twenty-seven parts and it spends roughly one night in each. Ancient sky-watchers in India noticed this and named each station after a prominent star or group of stars near it. These are the Nakṣatras, sometimes called lunar mansions.

The word itself is old. Lists of nakshatras appear in the Taittiriya Samhita and other Vedic texts, along with the deities associated with each: Agni for Krittika, Prajapati for Rohini, Rudra for Ardra and so on. Those lists begin with Krittika, the Pleiades. Later lists begin with Ashvini, a change that historians link to the slow shift of the equinox against the stars over many centuries†.

Older than the signs

The twelve zodiac signs (rashis) of 30 degrees each came to India through contact with the Hellenistic world in the early centuries CE. Greek-derived terms in Sanskrit horoscopy, such as hora, kendra and trikona, show that path; David Pingree's work on the Yavanajataka traces it in detail. The nakshatras were there first. The Vedic calendar, Vedic ritual and the Vedanga Jyotisha are built on the nakshatras, not on signs.

That is why we call them a sky map older than the zodiac. It is also why the two systems fit together slightly awkwardly: twelve signs and twenty-seven nakshatras share the same 360-degree circle, so each sign contains two and a quarter nakshatras.

The modern division

In classical astronomy each nakshatra is an equal segment of 13°20′ (thirteen degrees twenty minutes) of the sidereal zodiac, starting from 0° Mesha (Aries). Each is further divided into four padas (quarters) of 3°20′. Since 27 × 4 = 108 padas and 12 signs × 9 = 108, each sign holds exactly nine padas. The equal division is a mathematical convenience; the stars that gave the nakshatras their names are not evenly spaced, and some yogataras (junction stars) fall outside their own segments.

A twenty-eighth station, Abhijit, lying between Uttarashadha and Shravana, appears in some lists. It is retained in Muhūrta work but dropped from the equal twenty-seven-fold division.

The twenty-seven

1. Ashvini
2. Bharani
3. Krittika
4. Rohini
5. Mrigashira
6. Ardra
7. Punarvasu
8. Pushya
9. Ashlesha
10. Magha
11. Purva Phalguni
12. Uttara Phalguni
13. Hasta
14. Chitra
15. Svati
16. Vishakha
17. Anuradha
18. Jyeshtha
19. Mula
20. Purva Ashadha
21. Uttara Ashadha
22. Shravana
23. Dhanishtha
24. Shatabhisha
25. Purva Bhadrapada
26. Uttara Bhadrapada
27. Revati

Some can be matched confidently to modern stars. Rohini is Aldebaran, Chitra is Spica, Svati is usually identified with Arcturus, Jyeshtha with Antares and Magha with Regulus.

How nakshatras are used today

In the panchang. The Moon's nakshatra is one of the five limbs of the day, and the lunar month is named partly by the nakshatra in which the full Moon falls. Kartika, for example, is the month whose full Moon falls near Krittika.

In the birth chart. The nakshatra the Moon occupied at birth, the janma nakshatra, is a central datum in Indian horoscopy. Many families take the first syllable of a child's name from the pada of that nakshatra.

In time periods. The Vimśottarī daśā Daśā system, the most widely used scheme of planetary periods, starts from the Moon's nakshatra. Each nakshatra has a ruling graha in a repeating sequence of nine, and the fraction of the nakshatra the Moon has yet to traverse at birth fixes the balance of the first period. Our article on Vimshottari dasha explains this.

In matching. Several of the eight factors (kootas) in traditional compatibility checking, such as tara, yoni, gana and nadi, are read from the two people's janma nakshatras.

In choosing times. Muhurta texts classify nakshatras as fixed, movable, sharp, soft and so on, and recommend particular groups for particular undertakings.

Sidereal by nature

Because they are named for stars, the nakshatras are inherently sidereal: tied to the fixed stars, not to the equinox. That is one reason Indian astronomy kept a sidereal zodiac when Western astrology adopted a tropical one. The difference between the two, the Ayanāṃśa, is the subject of a separate article.

Reading the names

Many nakshatra names describe the shape of the star group or a quality associated with it. Ashvini is linked with the Ashvins, the twin horsemen; Mrigashira means "deer's head"; Hasta means "hand", and its five stars in Corvus are often pictured as an open palm; Shatabhisha means "a hundred physicians". Several come in pairs, the "former" (purva) and "latter" (uttara) Phalguni, Ashadha and Bhadrapada, each pair describing two halves of a larger figure. Reading the names alongside the sky is one of the simplest ways to see that the nakshatras began as observed star groups and only later became equal mathematical segments.

A note on sources

The Vedic nakshatra lists are discussed in the Vedanga Jyotisha and in later commentaries. David Pingree's studies of early Indian astronomy, and the editions of the Vedanga Jyotisha by K. V. Sarma with T. S. Kuppanna Sastry, are good starting points for the history.

Try it

The Nakshatra finder gives the Moon's nakshatra and pada for any date, time and place. The Panchang shows today's nakshatra, and the Dasha tool shows how the birth nakshatra sets the first period.

† Marked dates or readings are debated among scholars or still being confirmed by our faculty.