Fixed stars in astrology: precession, orbs and parans

Fixed stars are the bright stars that astrologers place in a chart alongside the planets: a star matters when it is conjunct a planet or one of the chart's angles. Astrology has worked with them since antiquity, and Ptolemy described most of the bright ones in terms of planetary natures. This section covers fifteen bright stars and explains how they are calculated and read.

What a fixed star is

The Greek word "planet" means "wanderer". Ancient observers set the seven wandering lights apart from the other stars, which keep the same constellation patterns night after night and were called fixed. The distances between them do not change within a human lifetime, so Aldebaran still marks the Bull's eye in the constellation Taurus, as it did in Ptolemy's time.

Two things follow for the chart. First, a star has no visible motion of its own through the signs, and it does not form the full range of aspects. Tradition mostly counts the conjunction, sometimes the opposition, and also parans, covered below. Second, a star sits in the same place in the charts of everyone born within a few years of each other. What makes it stand out in a particular chart is the planet or angle next to it.

Precession: why older positions are out of date

The vernal equinox, the starting point of the tropical zodiac, slowly drifts against the stars, so every star moves forward in the tropical zodiac by about 1° in 72 years, roughly 50″ a year. Over a century that adds up to almost a degree and a half.

Star positions printed in books from the middle of the last century are therefore out of date, and a conjunction worked out from them may not exist. The best known example is Regulus, long the star of late Leo: around 2012 it crossed into Virgo and now sits at its very beginning. Betelgeuse is now at the very end of Gemini and will cross into Cancer in about 60 years.

Each star page therefore shows the position for 2000 and for 1 January of the year given in the table; for a chart, use the position for the year of birth. The sidereal zodiac, tied to the stars, has no such drift, but its sign boundaries are shifted.

The orb of a conjunction

A star is a single point, and its orb is tighter than the orbs used for aspects between planets. The usual choice is about 1°, and the closer the contact, the more weight it carries. Wider orbs for the brightest stars appear in the literature, but they collect more chance conjunctions.

What counts first are conjunctions with the planets, including the Sun and Moon, and with the angles: the Ascendant, Descendant, MC and IC. The angles move about 1° every 4 minutes on average, so without an accurate birth time a star's conjunction with an angle cannot be established. A conjunction with a slow outer planet is shared by everyone born over a year or more, so it describes a generation more than a person. Brightness matters as well: a first-magnitude star is read as stronger than a faint one.

Most stars do not lie exactly on the ecliptic, and latitude complicates things. Spica and Arcturus both sit in late Libra, only about 0.4° apart in longitude, yet Arcturus lies some 31° north of the ecliptic. By longitude both are conjunct the same planet; in the sky they are far apart. For stars well away from the ecliptic some astrologers use parans instead.

A star's nature according to Ptolemy

In the first book of the Tetrabiblos, Ptolemy does not give a star a list of meanings. He describes it through the planets: a star acts like one planet or a blend of two. Most later authors built on this compact formula.

A few examples:

Regulus is of the nature of Mars and Jupiter. Hence its reputation as a star of authority, with a martial edge.
Spica is of the nature of Venus with a little Mars: softness with a small dose of resolve.
Algol Ptolemy describes together with all the stars of Perseus as Jupiter and Saturn; medieval authors counted it among the most difficult stars.
Vega and Fomalhaut are both of the nature of Venus and Mercury.

The formula suggests a tone, not a second planet: a conjunction with a star of Mars's nature sharpens the planet and makes it more decisive, while a star of Venus's nature adds softness and taste. Not every star in this section appears in Ptolemy: Achernar could not be seen from the latitude of Alexandria, and the nature given to it is a later addition.

The four royal stars

The royal stars are four bright stars spread around the zodiac: Aldebaran, Regulus, Antares and Fomalhaut. Each sits roughly in its own quarter of the circle.

By sign, Aldebaran, a star of the constellation Taurus, is now in the first third of Gemini, and Antares in the first third of Sagittarius, almost exactly 180° apart. A planet conjunct one of them is therefore opposite the other. Regulus is at the very beginning of Virgo, Fomalhaut at the beginning of Pisces. In Ptolemy three of the four carry Mars; Fomalhaut alone has the nature of Venus and Mercury.

Parans

A paran, from the Greek paranatellonta, means that a star and a planet stand on angles at the same time at the place of birth: the star rises while the planet culminates, for example, or the two set together. The method was popularised by the astrologer Bernadette Brady.

Parans do not depend on closeness in the zodiac. A star far from the ecliptic, such as Vega or Achernar, means little as a zodiacal conjunction but counts fully in parans. Parans depend instead on latitude: the same star and the same planet form a paran in one city and not in another. On an astrocartography map a paran shows up as a crossing of lines that acts along its whole latitude.

What the method does not promise

A fixed star refines what is already in the chart; a planet conjunct a star remains the same planet in the same sign, house and aspects. Tradition described the shade a star adds in its own time and language: the reputations of "fortunate" and "difficult" stars were set down by medieval authors and are not a forecast for any individual. This section describes the stars as part of the tradition and promises neither fame nor danger.

Stars in this section

Regulus: "little king", the very beginning of Virgo.
Aldebaran: the eye of the Bull, first third of Gemini.
Antares: "rival of Mars", first third of Sagittarius.
Fomalhaut: "mouth of the fish", beginning of Pisces.
Algol: an eclipsing binary, end of Taurus.
Spica: "ear of grain", end of Libra.
Sirius: the brightest star in the night sky, middle of Cancer.
Arcturus: "guardian of the Bear", end of Libra.
Vega: a former and future pole star, middle of Capricorn.
Betelgeuse: the red supergiant of Orion, the very end of Gemini.
Rigel: the "foot" of Orion, middle of Gemini.
Alcyone: the brightest of the Pleiades, the very beginning of Gemini.
Capella: "little she-goat", end of Gemini.
Pollux: one of the Dioscuri twins, end of Cancer.
Achernar: "end of the river", middle of Pisces.

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