Fixed Stars Calculator — Classical Conjunctions in Your Chart

Fixed stars are the bright background stars of the classical catalogue — the stars Ptolemy listed in the Almagest — called fixed because they keep a constant relation to one another, unlike the wandering planets. Traditional astrology reads them almost entirely through conjunction: a star whose longitude falls within a narrow orb of a natal planet or angle colours that point with the star's nature, as if the planet, ascendant or midheaven picked up a second voice. This tool checks the bright stars of the classical catalogue — the engine carries the brightest, magnitude-limited set with Robson-cited natures — against the seven classical planets and the four angles of your tropical chart.

A conjunction is a star and a natal point whose longitudes fall within orb of each other — the only contact this tool reads between fixed stars and the chart. The table shows the orb in degrees for every conjunction, sorted from the tightest to the widest: the tighter the orb, the more directly the star's nature speaks through the point it touches. A star can conjoin more than one point, so a single star may appear in several rows.

The royal stars are the four 'watchers' of the cardinal directions in the Persian tradition: Aldebaran (the Eye of Taurus) watching the east, Regulus (the Heart of Leo) the north, Antares (the Heart of Scorpio) the west, and Fomalhaut (the Mouth of the Southern Fish) the south. Each is a very bright star near the ecliptic, and in classical reading a royal star on an angle or a luminary was considered a mark of prominence — high visibility, and with it high scrutiny. They are flagged in the table.

The behenian stars are the fifteen stars of the Hermetic tradition, each bound to a planetary nature: Algol, Alcyone, Aldebaran, Rigel, Capella, Sirius, Procyon, Spica, Arcturus, Polaris, Alphecca, Antares, Vega, Altair and Deneb Algedi. The list was popularised in the West by Cornelius Agrippa's Three Books of Occult Philosophy (1533), drawing on older Hermetic texts that assigned each star its stone, plant and talismanic power. In practice the behenian nature colours the planet or angle the star conjoins, as if the star lent that point a second planetary voice. This tool reads stars through their Robson-cited natures rather than the talismanic tradition, so behenian membership is background knowledge here, not a separate result. Note a star can be both royal and behenian — Aldebaran and Antares are.

Vivian Robson's Fixed Stars and Constellations in Astrology (1923) is the standard public-domain compendium of star natures, gathering the significations of the classical and medieval sources (Ptolemy, the Hermetic texts, Al-Biruni and others) into one cited catalogue. Every nature shown in the table carries its Robson reference — page and quote where available — because this site's rule is that a traditional judgement is never shown without its source. The 1923 work is in the public domain, so the citations can be reproduced freely and checked by any reader.

Stars keep a constant relation to one another, but the zodiac itself drifts: the equinoxes slide backward along the ecliptic at about 50 arc-seconds a year — roughly one degree every 72 years — so a star's tropical longitude creeps forward over the centuries. Regulus stood near 0° of Leo in the classical era and has since advanced nearly a full degree a lifetime. This tool places the stars in the tropical zodiac, precession-adjusted to your birth date: the star longitudes are exactly where the sky put the stars on the day you were born, which is the figure classical technique works from. A star that was conjunct your Sun at birth stays conjunct through life — the conjunction does not drift with precession.