The lunar mansions are the 28 houses the Moon passes through on each turn around the zodiac, about one a day, and the tradition reads each as a kind of day; today they serve better as a symbolic calendar than as a forecast. It is worth understanding the calculation, the history and what is left of them, because the mansions appear in a lot of writing on magic and on choosing dates, almost always without explanation.

The calculation is simple. The Moon takes about 27.3 days to return to the same position among the stars, and the zodiac divided into 28 equal parts gives each mansion 12°51'26", which the Moon covers in a little under a day (0.98, to be exact). In the version that reached the medieval West and Agrippa, the first mansion begins at 0° Aries, the second at 12°51' Aries, the third at 25°43' Aries, the fourth at 8°34' Taurus. Since 28 is four times seven, the eighth mansion begins at 0° Cancer, the fifteenth at 0° Libra and the twenty-second at 0° Capricorn: the four points of the year always fall at the start of a mansion.

The idea comes from many places. In India they are the nakshatras, numbering 27 or 28; in China, the xiu, 28 lunar lodgings; among the Arabs, the manazil al-qamar, the stations of the Moon, tied to the rising of certain stars at dawn and to the forecasting of rain and seasons. The Quran mentions the stations of the Moon (36:39), and the manuals of astrology and magic, such as the Picatrix, associated a type of action with each mansion. Agrippa collected the list in the Occult Philosophy, with the Arabic names still in use.

The names recall stars and figures. The first, Al-Sharatain, means “the two signs” and points to the horns of the Ram; the third, Al-Thurayya, is the Arabic name of the Pleiades; the fourth, Al-Dabaran, is the star that “follows” the Pleiades, today called Aldebaran; the eighteenth, Al-Qalb, is “the heart” of the Scorpion, where Antares shines; the last, Batn al-Hut, is “the belly of the fish”.

Here comes an honesty that the manuals tend to omit. With precession, the stars that gave the mansions their names have slid about 26 degrees since Ptolemy, more than two whole mansions. The division into equal parts from 0° Aries is a convention of the tropical zodiac, which no longer coincides with the stars of the names, and whoever uses the mansions today uses a symbolic calendar, with the internal coherence that brings, without the observation of the sky that originated it.

To find the mansion of a Moon, take its longitude in degrees from 0 to 360 (0° Taurus is 30°, 0° Gemini is 60°, and so on), divide it by 12.857 and round up. A Moon at 10° Taurus is at 40°; 40 divided by 12.857 gives 3.11, and the mansion is the fourth. The Moon of your natal chart has a mansion, and the Moon returns to it every 27.3 days, which is the rhythm of the lunar return.

The degree counts. A Moon at 1° of a mansion has just entered it, and a Moon at 12° is on its way out; one way of thinking about this is to read the beginning as the foreshadowing of what is coming and the end as the echo of what has passed, and to leave the middle of the way for the full character of the mansion.

Each mansion received a list of uses: some served for journeys, others for weddings, planting, building, healing, study or rupture. The list varies from author to author, and that says something: when two traditions disagree about what a mansion favours, the reading is more symbol than table. We can use the mansion as a way of naming the day, as is done with the phase of the Moon, without expecting it to decide anything.

It is worth not confusing them with the phases. The phase measures the angle between the Moon and the Sun and speaks of waxing and waning; the mansion measures the position of the Moon in the zodiac and speaks of where it is. Both count, and a full Moon is possible in any mansion. The text on the Moon phases covers the first side of that conversation.

There is a curious consequence of this. Since the full Moon is always opposite the Sun, the mansion of the full Moon follows the Sun through the year: when the Sun is in Aries, the full Moon falls in Libra, in mansions 15 to 17; when the Sun is in Cancer, the full Moon falls in Capricorn, in mansions 22 to 24.

What human question lives here? Perhaps the one about how to measure the time that cannot be hurried. Lao Tzu wrote in the Tao Te Ching: “The great vessel takes a long time to complete.” The passage through the 28 mansions is a way of slicing a month into days with character, and we can read that cut as an invitation to patience, to look at what each day has of its own. The tension is in the return: if each day has a character, at what point do we stop living the day we have in order to live the calendar we read?

No study shows that the Moon in a specific mansion changes the outcome of a journey, a planting or a surgery. What exists is a tradition more than a thousand years old, which works as a calendar of attention. An important date for health, a legal deadline or safety is decided by whoever has competence over it, and the mansion enters, when it enters, within the possible window.

A practice with good sense is to note, for a month, which mansion the Moon is in each day and how the day went. After 28 observations you have a notebook of your own, which can confirm the tradition, contradict it or show something else. If you want to go further, you can find the mansion of your own natal Moon and see what it says about your way of feeling.

If you would like to follow the Moon month by month, the Lunar return shows the chart of the month that begins each time the Moon returns to the degree of your birth, calculated for the city where you will be. And the reading Spirituality and magic looks at your intuition, your gifts and the practices that tend to suit you.

The question that remains is: what would change in your month if each day had a name and you looked at it before deciding?

Some questions that tend to come up about the lunar mansions: