Yin Sha: by birth month, back two places a month

A six-month loop: Tiger in month one, Rat in month two

Yin Sha (阴煞) is set by the lunar birth month. Only the month matters, not the year or the day. Month one puts it on Tiger, month two moves it back to Rat, then Dog in month three, Monkey in four, Horse in five, Dragon in six, and month seven is back on Tiger, after which the pattern repeats.

Open the full-size diagram

Landings come from the site engine (iztro 2.6.0, default settings); arrows point in the direction of increasing month number.

The six landings in the picture form a loop and the arrows point the way the months increase: two places back each month, so six months use up all twelve places and return to the start. Twelve months therefore give only six landings, and two months six apart (month one and month seven, month two and month eight) share one. There is one more fact worth noticing: Tiger, Rat, Dog, Monkey, Horse and Dragon are all yang branches, and none of the six is a yin branch.

Twelve months, six landings

Put months and landings side by side and you get a six-row table. The last column gives the yin or yang of each landing, and every row is yang.

A quick check: someone born on the fifth day of the seventh lunar month is in the same slot as month one, so the landing is Tiger; someone born in the twelfth month shares a slot with month six, so the landing is Dragon.

1. 1

   Convert to lunar

   Match the solar birthday to the lunar calendar, checking Chinese New Year and leap months with extra care.

2. 2

   Fold to a slot

   Subtract six from any month above six to get a number from one to six.

3. 3

   Read the landing

   Numbers one to six give Tiger, Rat, Dog, Monkey, Horse and Dragon in turn.

The lunar month, not the solar month

Yin Sha uses the lunar month, so a solar date has to be converted first. Chinese New Year is where it goes wrong most easily: 9 February 2024 is still the twelfth lunar month and 10 February is the first day of month one, so their month numbers are twelve and one and their landings are Dragon and Tiger. The Hong Kong Observatory conversion table can be used to check the conversion.

A leap month is a second thing to settle. It is a repeated month, and the site splits it at the fifteenth: the first half of the leap month counts as that month and the sixteenth onward counts as the next. The year 2023 has a leap second month; here are three days converted:

Leap-month conversion shifts the month number for the whole chart; the background to the rule is in leap months, birth hour and day boundary settings.

The landing stays put; the palace name turns with the hour

Once the branch is fixed, what palace it is called depends on the Life palace, which is set by birth month and hour. For someone born in the first lunar month Yin Sha sits fixed on Tiger; the table runs the twelve birth hours of that one month and shows what the Tiger spot becomes:

Twelve hours, twelve palaces, and no repeats. So "which palace holds Yin Sha" is decided by month and hour together, and the month alone does not give a palace name.

Month stars, each with its own stride

Yin Sha is not the only minor star that follows the lunar month. Setting several month-based ones side by side shows what kind of stride it has:

Yin Sha is the only one that walks backward, and with a step of two. That is also why all its landings are yang branches: it starts on a yang branch and each step back of two keeps it on one.

Yin Sha is one of the minor stars set by birth month; the layers among main, helper and minor stars are in auxiliary, malefic and minor stars. For another star that follows the lunar month, read Tian Yao, and for opposite and flanking palace relations, see opposite, flanking and converging palaces.