Ardha Chandra Yoga: the half-moon shape, eight starting houses, and a rule BPHS borrows from Saravali

Ardha Chandra means half moon; Saravali also calls it Ardha Sasi, with the same meaning. It is the fifth of the seven-house shapes among the Nabhasa yogas, and it works differently from the other four. Nauka, Koota, Chatra and Chapa each name one block of seven houses, starting at one of the four angles. Ardha Chandra names every other block: seven consecutive houses, all occupied, starting anywhere that is not an angle. That makes it a family of eight shapes under one name. This page explains where the rule comes from (not where most readers would expect), how the engine tests it, how rare it is, and a chart from 2038. The general caution that applies to every yoga is set out in what a yoga in your chart means.

The rule: how Ardha Chandra Yoga forms

Saravali Ch. 21 Sl. 13: if the seven planets occupy seven houses continuously, commencing from a house which is not angular to the ascendant, the yoga is Ardha Chandra. The engine turns that into four checks:

1. 1.The seven grahas from the Sun to Saturn. Rahu and Ketu are not counted.
2. 2.Houses are whole signs from the Lagna.
3. 3.There is a block of seven consecutive houses starting at the 2nd, 3rd, 5th, 6th, 8th, 9th, 11th or 12th house - any house except the four kendras - that contains all seven grahas.
4. 4.Every house of that block is occupied, which means exactly one graha in each, and the five houses outside it are empty of all seven.

In the code this is a list of eight candidate blocks; the engine tries each in turn and reports the yoga, with the houses of the matching block, if one of them is filled. Only one can match, since a chart with one graha per house in one seven-house block cannot have the same in another.

Readings the engine settled

• "Not angular to the ascendant" is read as: the starting house is not the 1st, 4th, 7th or 10th. That is also what makes the five seven-house names fit together without overlap or gap, which suggests it is the intended reading.
• All seven houses filled. The rule says the planets "occupy seven houses continuously", and the engine uses the strict reading for every Akriti shape.
• Seven grahas only, following Saravali's "seven planets". All forming yogas reported: one graha per house is seven signs, which is Veena Yoga, set aside by BPHS Sl. 16-17 when another Nabhasa yoga forms but still shown by the engine.

What the classical texts say, and a borrowing in BPHS

The rule's home is Saravali Ch. 21 Sl. 13, which states it in the same sloka as Gada Yoga. In the BPHS translation in the corpus, Ardha Chandra has no rule-sloka of its own. After Sl. 14 gives the four angular seven-house shapes, a separate paragraph headed "Quoted from Saravali" supplies the non-angular case. The engine's code records this - "BPHS quotes Saravali Sl. 13 for this one" - and both BPHS files in the library carry the same insertion.

There is a second oddity in the same translation. BPHS Sl. 3-6, which lists the twenty Akriti names, prints "Ardh, Candr" as if they were two separate yogas, and does not list Yava, although Sl. 9-11 defines Yava and Sl. 29 gives its result. Counting "Ardh" and "Candr" separately is what keeps the list at twenty. Saravali's list of 32 has "Ardha Chandra" as one name and includes Yava.

On the result the two texts agree almost word for word. BPHS Sl. 40: the native will lead an army, have a splendid body, be dear to the king, be strong, and possess gems, gold and ornaments. Saravali Sl. 25 has the same list and adds that he will be fortunate. Neither text distinguishes between the eight blocks; one reading covers them all.

The app's sentence follows them closely: "Classically read as leadership, strength and a striking presence, favoured by those in authority and comfortable materially." The army becomes leadership, the king becomes those in authority, and the gems and gold become material comfort. Saravali Sl. 8-10 adds a general reading for all Akriti yogas - contentment with one's own fortune, earnings through a king - and BPHS Sl. 50 and Saravali Sl. 20-21 say the Nabhasa results hold through every period rather than one dasha.

Jyotisha Siddhanta Sara's yoga chapter (pages 145 to 154 of the scanned edition in the library) covers yogas from the ascendant, Raja yogas, lunar and solar yogas and exchanges, and does not include the Nabhasa shapes. Advanced Predictive Astrology and the Bhrigu Sutras do not mention Ardha Chandra Yoga either.

How rare it is: commonest of a rare family

Ardha Chandra formed in 2 of 3,000 sampled birth moments 1985-2060, or 0.1 percent - on 16 May 2038 and 15 May 2039. In the full walk of 20,000 moments (1985 to 2483) it formed 21 times. That makes it by far the most frequent seven-house shape in the walk: the four angular shapes together managed 8 (Nauka 2, Koota 3, Chatra 1, Chapa 2).

The reason is arithmetic, not astrology. Of the twelve possible seven-house blocks, eight carry the name Ardha Chandra and four carry the other names, so when the seven grahas do manage one per house across seven consecutive signs, the rising sign will usually make it Ardha Chandra. The hard part is the spread itself. On the engine's positions, all seven grahas lay inside some seven-house run in 1,340 of the 3,000 sampled moments, but filled every house of a run in only 4. Mercury stays within about one sign of the Sun and Venus within about two, so the three must still land in three different signs, and the Moon, Mars, Jupiter and Saturn must fill the remaining four exactly.

A consequence is that Ardha Chandra brackets every other seven-house shape. Scratch runs of the engine on the days of the walk's first Nauka, Koota, Chatra and Chapa moments all show the same thing: when the sign before or after rises, with the planets in nearly the same places, the engine reports Ardha Chandra instead. On 25 January 2207, for instance, it reports Ardha Chandra at 00:00 IST with Virgo rising, Nauka from Libra rising, and Ardha Chandra again at 02:30 with Scorpio rising. While a one-per-house spread lasts, the name changes with the hour; Ardha Chandra is what it is called for most of the day.

Worked example: 16 May 2038, early afternoon

The first moment of the engine's walk that forms Ardha Chandra is 16 May 2038 at 13:40 IST, New Delhi. It is shown as the engine's computation for that moment. Enter it in the birth chart calculator to check the figures. The ascendant is Leo at 21.41 degrees.

1. 1.Which block? The occupied houses are 8, 9, 10, 11, 12, 1 and 2 - a run of seven starting at the 8th, which is not a kendra. So the candidate is the 8th-to-2nd block.
2. 2.All seven inside it, one per house: Venus, Mercury, the Sun, Mars, Jupiter, Saturn and the Moon, in order. Holds.
3. 3.Houses 3 to 7 hold none of the seven; Ketu in the 5th does not count, and Rahu shares the 11th with Mars without affecting anything.
4. 4.The inner trio: Mercury one sign behind the Sun and Venus two behind, both on the same side, filling three consecutive houses.

The engine reports: "All 7 classical grahas (Sun through Saturn) sit in houses 8, 9, 10, 11, 12, 1, 2 of your chart, and each of those houses holds at least one - a Nabhasa "Akriti" (shape) Yoga." The interpretation line is the leadership sentence quoted above. The Sun in the 10th house fits the hour, early afternoon.

Two grahas are exalted here - Venus in Pisces and Jupiter in Cancer - and the Sun has only just entered Taurus. None of that matters to the shape. The engine's full report for the chart lists seven yogas: Anapha, Ubhayachari, Chandradhi (Adhi), Veena, Ardha Chandra, Sarala and Parivartana. Neither exalted planet is in a kendra, which is why no Panchamahapurusha yoga appears.

Ardha Chandra beside its siblings

The four angular seven-house shapes - Nauka, Koota, Chatra and Chapa - and Ardha Chandra are mutually exclusive and between them cover every seven-house block. A seven-house block always contains either two or three kendras: the blocks starting at an angle contain three, and every Ardha Chandra block contains exactly two. So Ardha Chandra can never coincide with Maala or Sarpa Yoga, which need three kendras occupied, while the angular shapes in principle can. Among the four-house shapes, BPHS names only those starting at a kendra (Yupa, Shara, Shakti, Danda); there is no four-house counterpart to Ardha Chandra.

What a yoga does not tell you

Ardha Chandra Yoga records that the seven grahas were spread one to a sign across seven consecutive signs, and that the rising sign put the start of that run off the angles. Both texts read leadership and royal favour into it. The reading does not change with which of the eight blocks is involved, and neither text ties it to a period. A rule this rare - 2 of 3,000 sampled moments - cannot be checked against lives in any ordinary way. It is a named rule about positions.

To see whether your chart forms Ardha Chandra or another Nabhasa shape, run the yoga calculator; it shows which houses your seven grahas occupy, and for this yoga it names the block it found.

Questions about Ardha Chandra Yoga

What is the rule for Ardha Chandra Yoga?

All seven grahas from the Sun to Saturn filling seven consecutive houses, one in each, where the block starts at a house that is not the 1st, 4th, 7th or 10th. Saravali Ch. 21 Sl. 13; BPHS Ch. 35 quotes Saravali for it.

Is Ardha Chandra in BPHS or only in Saravali?

Both name it, and BPHS Sl. 40 gives its result. But in the corpus translation of BPHS the rule itself appears in a paragraph marked "Quoted from Saravali", not in a numbered BPHS sloka.

How rare is Ardha Chandra Yoga?

It formed in 2 of 3,000 sampled birth moments 1985-2060. Over the engine's 20,000-moment walk to 2483 it formed 21 times, more than the four angular seven-house shapes put together.

Does it matter which house the block starts at?

Not for the classical reading: neither text gives the eight blocks different results. The engine reports which houses are filled, so you can see the block.

Why does my chart switch between Ardha Chandra and another yoga at different birth times?

Because the same arrangement of planets, counted from a different rising sign, fills a block starting at a different house. If the block starts at an angle it is Nauka, Koota, Chatra or Chapa; otherwise it is Ardha Chandra.

Does Ardha Chandra Yoga always come with Veena Yoga?

Yes, since seven grahas in seven houses occupy seven signs. BPHS Sl. 16-17 says Veena is not operable when another Nabhasa yoga is present; the engine reports both.