Sirius in the birth chart: the brightest star of the night sky

Star data

sefstars catalogue, Swiss Ephemeris 2.10.03.

Sirius is the brightest star of the night sky, and its Greek name means "scorching". Ptolemy gave it the nature of Jupiter with a little Mars, and astrologers have long linked it with prominence and ambition. In the tropical zodiac it stands in the middle of Cancer.

In the sky

Sirius belongs to Canis Major, and no other star outshines it at night. That brightness alone explains why astrologers treat it as a major star.

Part of the brilliance comes from nearness: Sirius is only about 8.6 light-years away, one of the closest star systems to us. The star itself is blue-white and about twice as massive as the Sun. A faint companion, Sirius B, circles it: a white dwarf about the size of the Earth that still holds nearly the mass of the Sun. The two complete an orbit around their common centre in about 50 years. The companion is around ten thousand times fainter than the main star, and Alvan Clark first saw it on 31 January 1862, while testing a new 18½-inch telescope lens. Sirius B is the remnant of a once larger star that used up its fuel and collapsed. Hubble pinned down its mass: the white dwarf's gravity is strong enough to stretch its light towards the red end of the spectrum, and that stretch gives about 98 % of the Sun's mass.

Sirius lies almost 40° south of the ecliptic, so a conjunction by longitude does not bring it close to the planet in the sky, and it is often worked with through parans. A person born in early July with the Sun on the degree of Sirius may have no Sirius paran with the Sun at all, while someone with no longitude contact may have one.

Finding it from Ukraine

Sirius is a star of winter evenings, best seen in the months around February. Orion leads to it: the line of the three belt stars, carried on to the south-east, points straight at Sirius. From Ukraine it never rises high. In Kyiv its greatest altitude is about 23°, in Odesa about 27°, so look for it low above the southern horizon.

Name and history

The name comes from the Greek for "scorching" or "burning". The word fits the Mars share in its nature. In astrological writing the image is one of heat and intensity: something that burns brightly and draws attention.

The name already appears in Hesiod, a poet of the eighth or seventh century BC. In Works and Days he describes the height of summer as the time when Sirius parches head and knees and the skin dries out in the heat. Aratus, in the Phaenomena, sets the star at the tip of the Dog's jaw and says that it blazes with the keenest, most searing flame. This is where the "dog days" come from: the name for the hot season when Sirius reappears in the dawn sky.

In Egypt the star was honoured as a goddess whom the Greeks called Sothis; Allen lists Egyptian forms of the name such as Sopet and Sopdit. Its first appearance before sunrise after a long spell of invisibility came just ahead of the yearly flooding of the Nile, on which the harvest depended. Plutarch called Sirius the "water-bringer", the star that brings the flood, and on the zodiac from the temple at Dendera the goddess Sothis appears beside two urns pouring out water, a sign of the flood. In Arabic it was called al-Shira. The name Sirius was approved by the International Astronomical Union in 2016.

Nature in the tradition

Ptolemy describes Sirius as having the nature of Jupiter with a little Mars. Jupiter is the main note: growth, honour, standing, a sense of having a place in the larger world. Mars adds heat and drive, the push to act on that sense rather than wait for it to be recognised.

Tradition connects Sirius with ambition, with public roles and with strong devotion to a cause. The Mars side gives the picture an edge: intensity that can overreach.

Of the two planets, Jupiter makes Sirius a generous star in most readings, closer in tone to Regulus than to Aldebaran, which Ptolemy gives the nature of Mars alone.

After Ptolemy

Agrippa's list of fifteen Behenian stars does not use the name Sirius at all. The star stands fifth as "the greater Dog-star", and right after it comes "the lesser Dog-star", Procyon, so the two dogs of the sky stay together, as they do in the constellations Canis Major and Canis Minor. Natal astrology still takes the nature of Sirius from Ptolemy rather than from this list.

Conjunctions with planets and angles

The usual orb for a conjunction by longitude is about 1°. Two examples of how tradition reads it:

• Sirius with the Sun. The Sun is the planet of identity and purpose, and Sirius heightens it: a strong wish to stand out and to give oneself fully to what one does.
• Sirius on the MC. The star's theme moves into career and public life. Tradition reads this as ambition aimed at a visible role and a reputation built on commitment.

Precession and the sign

Through precession Sirius moves along the zodiac by about 1.4° a century. It is now in the middle of Cancer, roughly fifteen and a half degrees, or about eleven centuries, short of Leo. A single century's shift is enough for positions in older books to be off by more than the usual orb.

The next star of this section further along Cancer is Pollux, near the end of the sign.

In celebrity charts

Conjunctions within 1° to the planets from the Sun to Saturn and to the chart angles.

• Boris Johnson: MC, orb 0°41′
• Elon Musk: Mercury, orb 0°46′

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