The Moon's nightly lodgings
The Moon is the fastest traveller in the sky. Where the Sun needs a year to cross the whole zodiac, the Moon makes the same circuit in about twenty-seven and a third days — quick enough that its place changes visibly from one night to the next. Long before horoscopes reached Arabia, desert sky-watchers marked that nightly progress against the stars themselves: each night the Moon "lodges" with a different small group of stars, and in roughly twenty-eight nights it has completed its round of the heavens.
Those lodgings are the 28 lunar mansions — in Arabic, the manāzil al-qamar, the stations of the Moon. Formally, each mansion is an equal arc of the ecliptic, about 12°51′ wide; twenty-eight of them tile the Moon's whole path. Among all the Moon transits an astrologer can follow, the passage from mansion to mansion is the one with a daily rhythm: moving some thirteen degrees in twenty-four hours, the Moon enters a new mansion about once a day. Each mansion carries the name of the stars that once marked it: al-Sharaṭān "the two signs" at the head of the ram, al-Thurayyā — the Pleiades, al-Dabarān "the follower" that trails them, and so on around the sky to the final mansion, Baṭn al-Ḥūt, "the belly of the fish".
The mansions are among the oldest layers of Arabic astrology. They grew out of the pre-Islamic Arabian star calendar — the anwāʾ, by which the risings and settings of star groups marked the seasons and the rains — and were later drawn into the formal astrology of the Islamic world. When al-Bīrūnī set out to teach the whole art in his eleventh-century Book of Instruction (al-Tafhīm), the mansions had their own place in the curriculum, enumerated star group by star group.
India counts the Moon's stations too. Traditional Arabian astrology synthesized knowledge from Babylonian, Sabian, Greek, and Vedic sources alongside their own, and the mansions are close kin to the nakshatras by which a Vedic natal chart reads the Moon: twenty-seven stations of 13°20′ each, with a twenty-eighth, Abhijit, in some of the oldest lists. Several were first marked by the same stars: the first nakshatra, Ashvini, and the first mansion, al-Sharaṭān, by the stars at the Ram's head; Krittika and al-Thurayyā by the Pleiades; Rohini and al-Dabarān by Aldebaran. In the Ptolemaic line that Canopy follows, traditional Arabian astrology uses the tropical zodiac, not the sidereal, as the seasons themselves were held to be a fixture of astrological influence, so Canopy divides the Moon's path into twenty-eight equal arcs counted from 0° Aries at the March equinox, while the nakshatras are counted in the sidereal zodiac.
Saʿd and Naḥs — the fortunate and the wary
What makes the mansions practical rather than merely descriptive is their temperament. The tradition classes each mansion as Saʿd — fortunate, auspicious — or Naḥs — unfortunate, calling for caution — with some falling in between. The names still carry the verdict: a run of mansions in the region of Capricorn and Aquarius are simply called the Suʿūd, "the lucky ones", and one of them, Saʿd al-Suʿūd, is remembered as the luckiest station of all.
This framing is the hinge between the mansions and the art of choosing times. Because the Moon presides over beginnings, the mansion it occupies colors whatever is begun that night: the Picatrix (Ghāyat al-Ḥakīm), the great medieval handbook of astrological practice, organizes whole chapters of elections and talismanic work mansion by mansion — this station favorable for journeys, that one for contracts, another for medicine, building, or planting, and others to be left well alone.
Read this way, the mansions become a calm nightly rhythm: not a prediction, but a weather report from the oldest continuous sky-watching system in the Arabian world — what tonight's sky is disposed toward, and what it would rather you postponed. Kept night after night, they amount to an astro Moon calendar: twenty-eight stations, each with its own temper, coming round in the same order with every circuit of the Moon.
How Canopy reads the mansions
Canopy carries the full catalog of all twenty-eight mansions, each with its name, its star group, its Saʿd or Naḥs temperament, and a reading drawn from the traditional astrologers and the classical sources.
Each night, Canopy tells you which mansion the Moon occupies, whether the tradition counts it fortunate or cautionary, and what it counsels for the day — in effect, a Moon alert for today. From a thin new crescent to May's full Flower Moon, every Moon is lodged in one of the twenty-eight, and the tradition weighed a beginning (a journey, a contract, a step in trade or career) by her mansion as well as her phase. Your natal chart records the mansion the Moon lodged in at your birth — a signature the tradition read with as much interest as the Moon's sign. And the electional tools take the mansions into account when scanning for a favorable window, so the Moon's station is weighed alongside planetary hours and dignities. A Home Screen widget keeps tonight's mansion in view without opening the app at all, and notifications can mark the Moon's entry into each new mansion and her monthly return to the mansion of your birth.
Questions
Is there a Moon alert today?
In a sense, every day has one: the Moon is always lodged in one of the twenty-eight mansions, and each is counted fortunate, cautionary or somewhere between. Canopy shows tonight's mansion with the day's guidance, can notify you when the Moon enters a new mansion or a new sign, and can warn you shortly before the Moon runs void of course.
What are the signs in the almanac?
They are the twelve zodiac signs the Moon passes through each month, printed day by day in farmers' almanacs to time planting, weaning and other everyday work, often beside the Man of Signs, a figure that gives each sign a part of the body from the head under Aries to the feet under Pisces. The custom is a folk survival of the medieval calendar tradition, which carried forward the older electional rule that the Moon colors whatever is begun under her. The lunar mansions measure the same monthly journey more finely, twenty-eight stations to the zodiac's twelve signs, and Canopy follows the Moon through them every night.
How do Moon signs relate to the lunar mansions?
The mansions divide the same circle more finely: twelve signs share it with twenty-eight mansions, so each sign spans about two and a third mansions. The Moon stays a little over two days in a sign but crosses into a new mansion about once a day. If you come to the mansions from lunar chart astrology, begin with the natal Moon: Canopy shows both the sign your Moon held at birth and the mansion it lodged in.
How can I find rasi and nakshatra by date of birth?
Your rasi, also written rashi, is the sign the Moon held at birth and your nakshatra the lunar station she lodged in; since the Moon moves about 13° a day, the date alone can leave either in doubt, and the birth time settles it. Canopy gives your Moon sign and the mansion the Moon held at your birth, both measured tropically, the reckoning of the Ptolemaic tradition it follows. To calculate sidereal chart positions instead, subtract about 24° from the Moon's tropical degree by the most common sidereal reckoning, a little less for earlier birth years: the sign it then falls in is your rasi, and each 13°20′ counted from 0° of sidereal Aries is one nakshatra, beginning with Ashvini.
Can I get a rashifal from date of birth?
A rashifal is a forecast read by rashi, the sign the Moon held at birth, and because the Moon spends only a little over two days in each sign, a date of birth alone can leave two candidate signs until the birth time decides. Canopy counts the Moon tropically, so the Moon sign it gives you is either your sidereal rashi or, more often, the sign after it. And rather than one forecast for everyone under a sign, its daily reading follows tonight's mansion and today's transits to your own chart.