Castor star meaning: the name Raʾs al-Tawʾam al-Muqaddam
The Castor star meaning begins with a pair. The Castor fixed star takes its Western name from one of the Twins of Gemini; in Arabic it is Raʾs al-Tawʾam al-Muqaddam, "the head of the foremost twin", the name Canopy prints beside it on the Chart tab and in the star picker, and in Castor astrology the app's natal reading glosses it "Head of the First Twin". The other head is Pollux, Raʾs al-Tawʾam al-Muʾakhkhar, the hindmost twin, just under three degrees farther along the zodiac.
The pair once marked the seventh lunar mansion, al-Dhirāʿ, the Forearm. By Canopy's tropical spans, Castor's degree now lies in the ninth, al-Ṭarf, the Glance (12°51′ to 25°43′ Cancer), a Naḥs mansion.
Where the Castor fixed star sits
By tropical longitude Castor stood at 20°35′ Cancer in 2025; Canopy's star page, moving it on for precession, shows about 20°36′ in late October 2026. The star lies about ten degrees north of the ecliptic and rises everywhere but the far south, beyond about 58°S. Though it is Alpha Geminorum, Castor is the fainter head: Canopy shows it at magnitude 1.58, and Pollux at 1.14.
Castor in astrology: a star of Mercury alone
Canopy files Castor as Mercurial, of the nature of Mercury alone: the only one of its 35 stars with that label, or with Mercury unmixed. Castor's star page shows the Mercurial badge and a single Mercury glyph; on the Today screen its contact reads "Star nature: Mercury", and when Castor is the day's leading contact, the card adds what to seek, intellectual excellence and artistic achievement, and what to avoid, overextension and nervous excess.
No star's nature enters the fixed-star talisman score. In the purpose elections, a Martial star's degree on an angle, Pollux's included, can set a window aside; Castor's never does.
Castor conjunct the Sun, Moon, Ascendant or Midheaven
Canopy calculates your chart from your birth date, time and place, and reads Castor by conjunction alone. When the star's degree, moved back for precession to your birth date, lies within three degrees of one of the seven classical planets, the Ascendant, the Midheaven, the Vertex or either lunar Node, the Chart tab lists the contact under Other Conjunctions, and the star page gives the reading, drawn from the classical sources: Castor "brings Mercury-like intellectual brilliance alongside potential for sudden fame or loss. When conjunct a natal planet, you have exceptional mental abilities and artistic talents, but must guard against nervous strain."
One reading serves every point: Castor conjunct the Sun or the Moon, Mercury or Jupiter conjunct Castor, Castor conjunct Venus or Saturn, Castor on the Ascendant or the Midheaven. Canopy does not vary it by planet, nor does it test the Descendant or the IC. A point between about 20½° and 23½° Cancer (2025 positions) also meets Pollux, whose own reading speaks of boldness and fighting spirit. The Sun crosses Castor's degree around July 12, so a natal Sun within orb belongs roughly to births from July 9 to 15.
How to make a Castor talisman: citrine, marjoram and Mercury
Castor is not one of the fifteen Behenian stars, and the classical Behenian lists give it no stone or herb. Canopy pairs it with citrine and marjoram all the same: the Correspondences card on Castor's star page names them as its gemstone and its herb, and its Traditional Uses line reads "Talismans for intellectual excellence and artistic achievement." The window page does not repeat the pairing; its About Castor row leads to the star page.
That is Canopy's whole prescription: a stone, an herb, the planet of the star's nature and the minutes, with no method of making. A talisman timed to Mercury himself, by his hour and his dignity, is another election: see the Mercury talisman.
When to make a Castor talisman: the Castor election
The Castor talisman and the Castor election are one search under two names. A moment qualifies only while Castor's zodiac degree is within one degree of the Ascendant or the Midheaven. Canopy tests the degree, not the star, which lies ten degrees off the ecliptic and reaches the angles at a different minute.
The Moon must be applying to Castor by conjunction, sextile or trine within two degrees: near 19° of Cancer, her own sign, for the conjunction, of Taurus or Virgo for a sextile, of Pisces or Scorpio for a trine. The Scorpio trine never passes: the Moon is in her fall there, and the one exception, a conjunction within that sign, cannot reach a star in Cancer. Nor may she be combust, apply a square or opposition to one of the five planets, apply to conjoin an afflicted planet or an undignified Mars or Saturn, or apply to the South Node; and Castor must have no Mars, Saturn, South Node or afflicted planet within three degrees. A moment that fails is set aside. In roughly the first three weeks of July, with the Sun near Castor, every conjunction is combust; the sextiles and trines lie far enough from the Sun to escape it.
A passing moment scores 6 points for a conjunction or 3 for a sextile or trine, 2 for the angle, and one each for a waxing Moon and a Moon not void of course: out of ten, Excellent from 70 percent, Good from 50. A waxing Moon at 19° Cancer, not void, conjoining Castor as its degree culminates scores 100 percent; add Mars at 22° Cancer and the moment is set aside. A waning, void Moon at 19° Pisces trining Castor as its degree rises scores 50 percent, still listed.
Windows last minutes, at most half an hour either side of the crossing. The shared rules are under fixed-star talisman windows in Canopy.
Finding a Castor window in Canopy
Open the Talismans tab and choose Fixed Star Talismans, or tap Fixed Stars in the Elections tab for the same search, titled Fixed Star Elections. The picker lists all 35 stars, the fifteen Behenian preselected: tap None, choose Castor, set the place and a range of up to about six months, and tap Search Stars. Scanning needs a subscription.
Filters on the form, for the Moon's phase and motion, the angle and the lunar mansion, narrow the results, which sort Soonest or Top Rated; with Castor alone, the al-Ṭarf filter leaves only the conjunctions. With your chart saved, each row adds a line on your natal Mercury. Each window opens on a page headed Castor Talisman or Castor Election, which gives its reasons under "Why this time?"
See whether Castor touches your chart, and when its degree next holds an angle.
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Questions
What does the Castor star mean in astrology?
Castor, in Arabic Raʾs al-Tawʾam al-Muqaddam, the head of the foremost twin, is a fixed star near 20° of tropical Cancer. Canopy files it as Mercurial, of Mercury alone, and reads it, drawn from the classical sources, as a star of intellectual brilliance and artistic talent.
What does Castor conjunct the Sun, Moon, Ascendant or Midheaven mean?
Canopy gives one reading for any classical planet, the Ascendant, Midheaven, Vertex or a Node within three degrees: Mercury-like intellectual brilliance, exceptional mental abilities and artistic talents, with potential for sudden fame or loss and a need to guard against nervous strain.
How do you make a Castor talisman?
Canopy pairs Castor with citrine and marjoram on its star page, gives its nature as Mercury, and times the work to the minutes when Castor's degree holds the Ascendant or the Midheaven while the Moon applies to the star. It gives no method of making.
When is the best time to make a Castor talisman?
When Castor's degree is within one degree of the Ascendant or the Midheaven and an unafflicted Moon applies to it by conjunction, sextile or trine within two degrees, with Castor clear of Mars, Saturn and the South Node. A waxing Moon conjoining it, not void of course, scores highest.
Is Castor a Behenian star?
No. Castor is not among the fifteen Behenian stars, and the Behenian lists give it no stone or herb. Canopy still pairs it with citrine and marjoram and finds its talisman windows like any other star's.
What is the difference between Castor and Pollux in astrology?
Canopy gives the Twins' heads different natures: Castor is Mercurial, of Mercury alone, a star of the mind and the arts; Pollux is Martial, of Mars alone, a star of courage and fighting spirit. Under three degrees apart, both can touch one natal point.
