Encyclopedia

The angular figures a chart draws between bodies, the reason the tradition allows exactly these, and why the orbs around them are convention.

Three defensible answers to when a cross-quarter day falls: the fixed calendar date, the solar-longitude midpoint, and the temporal midpoint of the season.

Alexandrian astral material reached Tang China through Indian and Iranian intermediaries, by the same routes and the same translations that carried it west.

Domicile, exaltation, triplicity, bound and face: the fivefold scheme, its sources, and the three places where the surviving texts do not agree.

Sanskrit horoscopic vocabulary carries Greek technical terms, and what that does and does not establish about how the two traditions met.

Before calendars were reliable, the year was told by which stars were visible at dawn. The mechanism, the texts that use it, and why the dates drift.

Seven house systems divide seven different objects into twelve, which is why a chart tool that offers all seven never agrees with itself.

The slow westward slide of the equinox against the stars: the rate, who first measured it, and why it separates the seasonal frame from the stellar one.

The division of a chart by whether the Sun stood above or below the horizon at birth, and the largest doctrinal gap in twentieth-century astrology.

Four instants whose calendar dates move. What they are, why the date shifts between years, and what pre-Christian Europe is recorded as having marked.

What the empirical tests of astrology show, why the most-cited result is not the strongest one, and what a test like this cannot settle.

The four points where the ecliptic crosses the horizon and the meridian, how fast they move, and the latitudes at which they stop existing.

Calendar-making as a prerogative of state, the bureau that did it, and the prosecution of 1664 to 1669 that ended in a shadow measurement.

An identical, mostly flattering personality sketch reads as a precise account of one person: the 1949 demonstration, its real numbers, and why.

Months set by conjunction, a solar year cut twenty-four ways, the leap-month rule, and the change from equal time to equal solar longitude.

Greek and some Sanskrit scientific works entered Arabic in Abbasid Baghdad across two centuries, sponsored partly by a court invested in astrology.

A week-based two-season year with a leap week instead of a leap day, described by the people who used it and computable to the day for any year.

Children born just after a school cutoff are nearly a year older than classmates, and it shows in test scores, sport selection, and later life.

The twelve-paragraph newspaper horoscope is a commercial format of the 1930s, produced by a printing constraint, and it has no premodern precedent at all.

In the twelfth century, Arabic astronomical and astrological texts, Greek and Arabic in origin alike, were translated into Latin, chiefly from Iberia.

The tropical zodiac, the sidereal zodiac and the IAU constellation boundaries divide the sky for three different purposes, and answer three questions.

The Mesopotamian god of the abyssal waters, and the single figure standing behind three of the twelve zodiac constellations.

The opening of summer in medieval Ireland, the one described rite among the four quarter-days, and why the maypole belongs to a different tradition.

The thinnest attested of the four Gaelic quarter-days: a name, a season, ewes coming into milk, and no described rite anywhere in the early sources.

Two well-recorded Slavic folk observances, their Christian calendar hosts, and why the eightfold Slavic wheels circulating online are recent compositions.

The opening of harvest, the assembly at Tailtiu, and the one festival in Britain and Ireland with a serious documented case for long-term continuity.

The autumn equinox station of the modern eightfold year, named in 1974 after a Welsh literary figure who has no calendrical association of any kind.

The best-documented seasonal fire custom in Europe is medieval and Christian, attached to 23 June, and it drifts against the solstice it is named for.

A spring-equinox festival named in 1974 after a goddess inferred in 1835 from a month name recorded in 725. The three steps come apart cleanly.

The opening of winter in medieval Ireland, the royal assembly that met at it, and why the usual Halloween and All Saints story gets the chronology backwards.

The eight-festival cycle has three separate provenances, no historical community kept all eight, and it was assembled in Hertfordshire around 1958.

A midwinter season rather than a solstice-day festival, and the reason the Christmas and Sol Invictus story is weaker than it is usually told.

Named Beginning of Death in Hellenistic Greek and the sign of death by Dorotheus, an exact agreement across two independent lines of transmission.

The House of the Good Daemon in Ptolemy's own words, ranked third-best by Dorotheus, and Jupiter's joy since Firmicus and still in Lilly.

Called Good Fortune in Hellenistic Greek and the house of the child by Dorotheus, who ranked it fourth of the twelve places by strength.

The place of the Ascendant itself, the Horoskopos that gave the word horoscope its name, and the one house nearly every named source ranks first.

The lower midheaven and cardine of the earth, ranked sixth-best by Dorotheus, though Ptolemy's own method for parents never names it.

Named God for the Sun in Hellenistic Greek, and the Sun's own joy from Firmicus through Lilly, thirteen centuries and one language apart.

The house of livelihood and movable goods, named the Gate of Hades in Hellenistic Greek, a name Ptolemy records but does not himself use.

The Occident, built on the Descendant, called the sign of marriage by Dorotheus and one of the few places Ptolemy's own prose names directly.

Called Bad Fortune in Hellenistic Greek, ranked among the two weakest of the twelve places by Dorotheus, and given as Mars's joy since Firmicus.

The Midheaven itself, ranked second-best of the twelve places by Dorotheus and, for Ptolemy, one of his few directly named technical terms.

Named Goddess for the Moon in Hellenistic Greek and called her joy by Dorotheus, though Ptolemy's own method for siblings never mentions it.

The House of the Bad Daemon, a place Ptolemy names only to say it should be disregarded, ranked worst of the twelve by Dorotheus, and Saturn's own joy.

A ninth-century Baghdad astrologer whose two major works, each translated twice into Latin, were among the widest channels astrology used to reach Europe.

An eleventh-century polymath whose astrology manual is technically rigorous, written by a man who never states outright whether he believed the doctrine true.

The name attached to more of this site's material than any other, and the man underneath it, who names six of the twelve places and is silent about the rest.

The most-cited author on this site, whose Greek is lost, and whose ranking of the twelve places is assembled here from the house entries, one place from each.

An astrologer at the earliest Abbasid court, credited with electing the moment for founding Baghdad in 762; his own writing survives only in later epitomes.

The most consequential transmitter in modern astrological software, whose tables most programs ship under somebody else's name.

The brightest true planet after Venus, completing the ecliptic in under twelve years, roughly a sign a year, which makes it useful for marking long periods.

The reddest of the five true planets, with the widest brightness swing and the largest retrograde loop of the seven, both from its varying distance.

Mercury never strays far from the Sun and is visible only near dawn or dusk. It is also the one planet exalted in the sign it already rules.

The fastest of the seven, covering about 13 degrees a day, which makes it the body most sensitive to an error in birth date or time zone.

The outermost classical planet: its Greek and Babylonian names, its dignities, the sect rule that governs it, and where the modern Saturn return came from.

The Sun rules one sign, holds no bounds, and is the only body whose sign depends on date alone, which is why a newspaper column could use it.

Venus was two names, a morning star and an evening star, before the recognition that they were one body collapsed the naming into one.

An English and Germanic custom with several centuries of records, routinely filed under an Irish festival it has no attested connection to.

One chapter of an eighth-century textbook on time-reckoning, the only surviving account of the pre-Christian English calendar, and what it does not say.

A bronze plaque from Roman Gaul, in Gaulish, recording a five-year lunisolar cycle. The only calendar document from a pre-Christian Celtic-speaking people.

A very large corpus of Latvian folk songs collected in the nineteenth century, and what a late collection of oral material can and cannot establish.

Ptolemy's four books on astrology: what the work is for, how it reached the present through three languages, and why its chapter numbers must be named.

A Sanskrit astrological text long dated to the second and third centuries CE on readings its manuscripts do not contain, and the correction that followed.

A Sanskrit astronomical treatise reached Baghdad in the 770s, became an Arabic zīj, and by that route entered Latin Europe.

Aquarius's Babylonian name is a status title meaning great one. The water imagery comes only from the god's picture.

Aries opens the tropical zodiac at the March equinox itself. Its Babylonian figure was a hired farmhand, the ram a later Greek addition.

The second-narrowest of the twelve like-named constellations, and the one whose divine counterpart may have been an empty shrine rather than an animal.

A goat with a fish's tail is not a natural animal, and it is the one zodiacal hybrid that survived Babylon to the present essentially unchanged.

The Ptolemaic bounds of Gemini split the transmission: Lilly's row, which most software ships as Ptolemaic, disagrees with every Greek edition.

The Sun's sole domicile, and home to Regulus, one of the four bright stars near the ecliptic.

The only sign figured as an object: a Babylonian balance, a Greek claw, and a Roman restoration credited to Julius Caesar.

Zero degrees of tropical Aries currently falls inside the constellation Pisces: the concrete case behind the whole tropical-versus-sidereal question.

The composite Mesopotamian god Pabilsag was carried into Greek astrology as a plain archer: the clearest case of simplification among the twelve signs.

Of the thirteen constellations the ecliptic crosses, Scorpius is the narrowest by far, and its missing claws are doing duty as Libra's scales.

Taurus is a straight translation of the Babylonian Bull of Heaven, but its real distinction is the Pleiades and Hyades within it.

The sixth sign was a furrow before it was a virgin, and the name of its brightest star still carries the ear of grain the Babylonian figure held.

A modern label for the Indian astrological tradition, and what the textual record does and does not support about the antiquity it claims.