Nakkhattapadāni "lunar mansions" and subdivisions

[alexcc0]

A nakkhatta (Skt: Nakshatra) is one of 27 “lunar mansions”. These are described in the early Vedas with a story of Chandra (Moon) visiting his 27 wives each night of a sidereal month. In later texts, predating the Buddha, these are further divided into four pāda (steps) each, giving us a total of 108 nakkhattapadāni (most certainly the origin of 108 mala beads).

Currently, these are too broadly defined in the glossary as “constellations”. A nakkhatta (13° 20’) is often named after a single star, cluster, an asterism at most, or more accurately a “lunar mansion”. While a pāda is smaller still, much too small (3° 20’) to be a “constellation”.

To give an idea of the size, the distance between Orion’s shoulders is almost three pāda. The three stars of his belt span one pāda. The angular distance between the twin heads of Castor and Pollux are more than two pāda. Whereas a “constellation” (Skt: “rasi”) can easily span several nakkhatta and dozens of pāda.

I am not aware of an common English translation for nakkhattapadāni, but perhaps “ecliptic step” or “lunar path step” may succinctly explain its meaning?

The nakkhattapadāni were (and still are) significant to Vedic astrology and rituals, they were crucial for determining tithi (lunar days) to accurately predict synodic moon phases weeks in advance. The Buddha was silent about most of these details, but he required monks to anticipate the full moon and conjunction, and required forest monks to be familiar with the cardinal directions, 27 nakkhatta, current position of the Moon among the stars, and suggested learning the 108 pāda.

Twelve of the 27 nakkhatta names give us the Buddhist lunar months, many named after a specific star or cluster. Kattikā (Kṛttikā, “Cutters”, Pleiades) would have been understood as the first nakkhatta in the time of the Buddha (although due to precession, poorly understood, Pleiades could not be observed with the vernal equinox). Māgasira (“Stag head”, head of Orion). Maghā (“Mighty”, Regulus of Leo), two nakkhatta later is the month of Phagguna (“Reddish one”, Denebola, tail of Leo), Cittā (“Bright”, Spica of Virgo).

In the Vinaya is a discussion of forest dwelling conduct, with the snippet:

na nakkhattapadāni jānanti, na disābhāgaṁ jānanti

I believe should be (“did not know the subdivisions of the lunar mansions nor cardinal directions”) or perhaps more simply (“did not know the lunar position among the stars nor cardinal directions”).

kattaradaṇḍo upaṭṭhāpetabbo, nakkhattapadāni uggahetabbāni—sakalāni vā ekadesāni vā, disākusalena bhavitabbaṁ.

Perhaps something like (“a celestial measuring rod should be available, the lunar mansions should be learned – the 27 entirely or the 108 parts in detail, and he should become skilled in the cardinal directions”).

nakkhattaṁ sappadesaṁ vā,

(“the 27 lunar positions or 108 parts”).

Of course the numbers are not mentioned here in the Pāli, but I think the numbers best explain what the Buddha is referring to, for those of us less familiar with Indian sidereal astronomy.

[alexcc0]

Below is a simulation of the future Full Moon seen from Europe on the nights of 11 June (right), 12 June (middle), 13 June (left).

We can imagine intermediate lunar positions, witnessed near sunrises and sunsets, and perhaps as seen from the other side of the Earth (maybe in Australia). We would expect the Moon to appear to travel approximately one pāda (3° 20’) every six hours.

However, due to apogee, I believe the Full Moon will appear to move a bit more slowly across the stars.

[alexcc0]

The brightest stars and their pāda were memorised, the current positions of the Sun and Moon were observed, and their “angular velocities” were understood. The Sun moves 1 pāda East every 3-4 days and the Moon 12°-15° or 3-5 pāda East per day. Indeed, the Vedanga Jyotisha describes mnemonic systems whereby each nakkhattapāda is assigned a unique syllable from the Pāli/Sanskrit alphabet. From Kattikā: A, I, U, E, then Rohinī: O, Va, Vi, Vu, Māgasira: Ve, Vo, Ka, …, etc. I understand, even today, many Indian children are named based on the nakkhattapāda position of the Moon at the time of their birth.

Garlands of 108 mala beads were later used for astrology and rituals. It’s debated whether mala beads existed at all in the time of the Buddha (I would guess yes). Colored or textured mala beads are useful as a “road map” of the fixed stars and nakkhatta. But perhaps mala beads are less practical for tracking the positions of the planets (wandering stars) or the fast moving Moon in particular. I’ve tried moving bits of string around – it’s possible but frustrating.

How might a forest monk have kept track of the solar and lunar positions as the Buddha required? Certainly, monks were not meant to waste much time on this activity. Perhaps they moved stones from divet to divet (like the mancala game known to have existed since 5800 BC) in wood, stone, or dirt. Or perhaps they used 27 or 108 sticks in a circle (perhaps a function of kattaradaṇḍo).

Here’s a physical representation of the nakkhattapadāni with paper on a table rather than out in the forest. The outer 27 nakkhatta are sidereal and the inner 12 signs (Skt: Rāśi) are tropical (aligned with the equinox and seasons, not their namesake constellations). The tea lights helped to divide a circle into 27 parts, but perhaps one candle could be lit on its corresponding Uposatha day.

The outer stones represent the visible planets. The big red stone in Rohinī (pāda 4) represents the Sun. The white stone in Cittā (pāda 4) represents the Moon. The wooden stick points from the Sun opposite the Moon where/when I expect they will align for the Full Moon in five days. The inner stones represent some bright ecliptic stars (purple Pleiades in Kattikā p4, orange Aldebaran in Rohinī p2, red Betelgeuse, blue Regulus, purple Spica in Cittā, etc).

Suppose I observed the Moon earlier today 6 June in Cittā (p1 just west of Spica p3). I would naively assume the Moon will appear in each subsequent nakkhata night after night. However, I may have noticed that the Moon is in apogee, appears smaller and moves half a pāda slower this week. Rather than the average 4 pāda per day, the Moon will move 7 pāda in two days. Thus from the edge of Cittā tomorrow, Sāti p4, Vesākha p3, Anurādhā p3, and the Moon will be in Jeṭṭha p2 then p3 several hours into 11 June.

Only during a solar eclipse can naked eyes see the Sun against the stars. But if I had kept accurate records since the previous Full Moon (or consulted the NASA JPL website) I might have known that the Sun was in Rohinī p4 earlier today. I estimate the nakkhatta border tomorrow and the Sun in Māgasira p1 the following day June 9 and p2 by June 11.

We will observe the Jeṭṭha Full Moon then or the day after. NASA tells me 11 June 7:43 UTC exactly. We can similarly predict future Moon phases from any previous Moon phase. There are over six or under nine days between phases depending upon apogee (smaller, slower), perigee (bigger, faster), or just over seven days on average.