Zodiac sign
BabylonianHellenisticModern WesternHistorical scholarshipTraditional doctrineAstronomical factEditorial synthesis
Definition
One of the twelve equal thirty-degree divisions of the ecliptic. A sign is a measured segment of a circle, and is not the same thing as the constellation of the same name.
Also called: Sign · Degree in sign
In more depth
The zodiac is the band of the ecliptic divided into twelve equal parts of thirty degrees each. Every sign is therefore the same width by definition. The scheme of twelve equal divisions is inherited from Babylonian practice and became standard in the Hellenistic tradition that Western astrology descends from.[1][2]
The constellations that lend the signs their names are a different thing entirely: the International Astronomical Union defines 88 constellations as regions of the sky with unequal sizes and irregular boundaries. A sign is a unit of measurement along the ecliptic; a constellation is a patch of sky. Conflating the two produces most of the confusion about whether signs have 'shifted'.[3]
References
Numbered citations in the text link to the records below; each record links to the full source registry.
- Francesca Rochberg. The Heavenly Writing: Divination, Horoscopy, and Astronomy in Mesopotamian Culture. Cambridge University Press. 2004. Historical scholarship View source record
- Chris Brennan. Hellenistic Astrology: The Study of Fate and Fortune. Amor Fati Publications. 2017. Modern practitioner interpretation View source record
- International Astronomical Union. The Constellations (official list of the 88 IAU constellations). current (living reference page). Astronomical fact View source record