Sun
The Sun’s yearly circuit of the ecliptic is what the ecliptic is measured against: the twelve tropical signs are twelve equal divisions of the path the Sun traces against the background of stars in the course of a year, and the Sun advances along it at a nearly constant rate of a little under one degree a day. That single fact sets the Sun apart from every other body a chart places. Its sign depends on the date of birth alone. No other placement in a chart works that way; the Moon changes sign every two to three days, and the ascending sign changes roughly every two hours, so both need a birth time and the Sun does not.
Because the Sun’s own motion defines the frame every other body is measured against, it has no retrograde phase and no elongation limit of its own. Those two concepts, central to how Mercury, Venus, Mars, Jupiter and Saturn are each described, apply to the Sun only in reverse: it is the reference point the other six are timed against.
The names
The five other planets carried a Greek descriptive epithet before they carried a god’s name: Saturn was Phainon, “the shining one,” before it was Kronos 1. The Sun did not go through that stage. Its Greek name was Helios throughout, a god-name from the start, and the same appears to hold for the Moon under Selene. The Latin name is Sol, preserved directly in the Romance weekday names.
In Akkadian the sun-deity is Šamaš, also the Mesopotamian god of justice, an association that survives into the Hellenistic period’s own reasoning about the Sun’s nature 1.
Dignities
| Domicile | Leo |
|---|---|
| Detriment | Aquarius |
| Exaltation | Aries, at 19 degrees |
| Fall | Libra, at 19 degrees |
| Triplicity | Fire (by day) |
| Bounds held (Egyptian) | none |
The Sun rules Leo and no other sign, the only planet besides the Moon to hold a single domicile where the five non-luminaries each hold two. It takes no bounds at all: the Egyptian bound scheme divides each sign among the five non-luminaries only, and the Sun and Moon are absent from that table by construction. The Sun rules the Fire triplicity by day and is exalted in Aries, falling in the opposite sign, Libra. Why the domicile scheme splits outward from the Sun and Moon’s own signs, Leo and Cancer, in order of each planet’s distance from them, is set out in full at Saturn, which holds the two signs the symmetry places furthest out. The whole apparatus, including the separate and older stream of material the Sun’s own exaltation degree in Aries descends from, and where each of its five parts is textually secure or contested, is at Essential Dignity.
Sect
The Sun is a diurnal planet, and more than that: in a chart of the day it is the sect light itself, the luminary that names the chart’s sect, with the Moon holding that role at night. See Sect for the full division of the seven planets into a day team and a night team and for how Mercury’s membership is decided separately from the other six.
Tradition
Held byClaudius Ptolemy, Tetrabiblos bk. I ch. 4, Alexandria, c. 150 CE
Ptolemy’s account of the planets proceeds from a physics of the four qualities rather than from a list of significations. He gives the Sun a predominantly heating and secondarily drying power: “The active power of the sun’s essential nature is found to be heating and, to a certain degree, drying” 2 bk. I ch. 4. Every solar signification in his later chapters is presented as a consequence of that physical account.
Tradition
Held byWilliam Lilly, Christian Astrology bk. I, London, London, 1647
Lilly’s chapter on the Sun works through the same fixed template he applies to every planet: nature, colours, kingdoms and trades under its rule, the parts of the body, and the kinds of person a questioner might be asking about. It is written for a practitioner judging a specific question put by a client, and it should be read as that kind of working reference 3 bk. I.
What the Sun’s sign became in public
The fact that opens this entry, that the Sun’s sign is the one placement a birth date fixes without a birth time, is also the entire explanation for why the twelve-paragraph newspaper horoscope exists in the form it does and could be produced for a mass readership at all. That history, the format’s actual date of origin, and the technical tradition’s much smaller regard for the Sun’s sign relative to the ascendant, are set out at The Sun-Sign Column.
Gap in the evidence
Whether the Sun and Moon ever carried a separate descriptive epithet in Greek before Helios and Selene, in the way Saturn was Phainon before it was Kronos, is not established from the sources consulted for this entry. The absence of such an epithet for the two luminaries may be a real asymmetry in how the seven were named, or it may only reflect what has survived; nothing here resolves it.
References
- Claudius Ptolemy, trans. F. E. Robbins. Tetrabiblos. Loeb Classical Library 435. Cambridge, MA: Harvard University Press, 1940 (composed c. 150 CE). bk. I ch. 4. find a copy (catalogue search) recordprimary source
The standard English reference and the chapter-numbering scheme this site adopts and names. Non-Robbins reprints number the chapters differently, so every locus here is given as Robbins numbering.
- William Lilly. Christian Astrology. London, 1647 (composed 1647). bk. I. https://archive.org/details/b30338724 recordprimary source
Second edition 1659. Where a figure differs between the two printings this site says which printing it is quoting.
- Nicholas Campion. A History of Western Astrology, Volume I: The Ancient and Classical Worlds: Continuum, 2009. ISBN 9781441127372 recordscholarly
The standard single narrative survey. Volume I first appeared as The Dawn of Astrology, Hambledon Continuum, 2008. The subtitle is "The Ancient and Classical Worlds", not "The Ancient World"; the shortened form is widely miscited.