Algol

Meaning

Algol is the second-brightest star of Perseus. In the old star maps it marks the head of Medusa, the Gorgon the hero holds up in one hand. Its name comes from the Arabic ra’s al-ghūl, “the head of the demon”.

It is a star that winks. About every 2 days and 21 hours, it fades from magnitude 2.1 to 3.4 for a few hours. The cause is an eclipse: Algol is a pair of stars, and the dimmer one passes in front of the brighter. It lies some 90 light-years away.

Its degree was 26°10′ Taurus in 2000, and it moves forward about a degree in 72 years. It lies about 22° north of the ecliptic, so a planet on its degree is far from it in the sky. Some astrologers give such a contact less weight for that reason.

Algol has the hardest name in astrology. Tradition, following Ptolemy, gives it the nature of Saturn and Jupiter, and the old authors called it the most unfortunate star of the sky. They read it as danger and violent passions. Many modern astrologers read the same star as raw intensity: strong passions, deep anger and great power. Such forces can wound or protect, depending on how they are held. Either way, the star marks a strong current to work with, not a sentence.

In practice

• On the Sun or the Ascendant, Algol is read as a powerful presence that draws strong reactions, and a need to handle one’s own intensity with care.
• On the Moon, it is read as deep feelings, sometimes fierce, which gain from being named and expressed rather than held in.
• On Mars, it is read as great energy and a fighting spirit, at its best in defence of others.
• Read in context. A contact with Algol is one note in a whole chart, read with the planet’s sign, house and aspects, never alone.

Across traditions

• Greek myth, in Ovid’s telling, makes Medusa a beautiful woman turned into a monster whose gaze changed onlookers to stone. Perseus cut off her head and used it as a weapon. Many modern writers now read her as a figure of injustice and of rage that has its reasons.
• Chinese astronomy calls it 大陵五 Dàlíngwǔ, the fifth star of the Great Mausoleum.
• Indian astrology does not count it among the stars that mark the nakshatras.

Origin and history

Ptolemy’s Almagest lists Algol as the bright star in the Gorgon’s head. Medieval Latin texts called it Caput Algol or Caput Medusae. Medieval magic also counted it among the fifteen Behenian stars, and Agrippa lists it in his De occulta philosophia. In 1783 the young English astronomer John Goodricke measured its period and suggested that a darker body passes in front of it. Vivian Robson, in 1923, gathered the old readings. Bernadette Brady, in 1998, reread the star through Medusa’s myth.

How Ulune calculates it

Ulune places Algol from the Swiss Ephemeris star catalogue, sefstars.txt, where it is Beta Persei. Its position is the apparent one at the chart’s moment, with precession, nutation, aberration and the star’s own motion applied. Ulune does not follow its changes in brightness.

A body within 1° of Algol’s longitude counts as on it. Its ecliptic latitude is not compared, so its 22° above the ecliptic does not change the contact. The Stars part of the chart table lists every body, point and angle on the star except the lots, closest first. Without a birth time, a contact that may not hold all day is marked ~. On the wheel, Algol is an overlay turned on in the Bodies panel. Its mark names the closest of the Sun, Moon, Mercury, Venus, Mars or the four angles within 1°.

Correspondences