Sun (astrology)

Definition

The Sun in astrology is the greater of the two luminaries and the body whose yearly path defines the zodiac. Ptolemy gave it a heating and somewhat drying power and called it masculine and diurnal. The "sun sign" is the sign the Sun occupies at birth, which modern astrologers read for a person's core identity.

Primary source

The active power of the sun's essential nature is found to be heating and, to a certain degree, drying.

— Ptolemy, Tetrabiblos I.4, Of the Power of the Planets, trans. F. E. Robbins (Loeb Classical Library 435, Harvard University Press, 1940). Open-access copy

Deep Understanding

Ptolemy describes every planet through the four qualities of ancient physics, and he starts with the Sun because its effect is the easiest to see. Its heat, he says, is plain from its size and from the seasons: the higher it climbs toward the zenith, the more it warms us. He then describes other planets by their distance from it. Mars is dry and burning because the Sun's sphere lies just below his, and Mercury dries because it never strays far from the Sun's heat.

The Sun also sets the frame of the chart. Ptolemy grants that a circle has no natural beginning, but he reports that the zodiac is counted from the sign that begins at the spring equinox, Aries, and the Sun spends about a month in each sign. He gives the Sun Leo as its house, Aries as its exaltation, because there the days begin to lengthen, and Libra as its depression. He reports that the ancients gave the Sun and Mercury a common nature that takes on the character of whichever planets they are joined with, and in the chapter on parents he links the Sun and Saturn with the father.

In the cosmology of the seven spheres the Sun's sphere sits in the middle, with Mercury, Venus and the Moon below it and Mars, Jupiter and Saturn above, and Gnostic readers counted it among the seven planetary rulers of the hebdomad. The newspaper horoscope, which sorts readers by Sun sign alone, is a twentieth-century form. It grew out of R. H. Naylor's horoscope for the newborn Princess Margaret in the London Sunday Express in August 1930. Modern astrologers read the natal Sun's sign and house for identity and purpose, and many of them add that the Sun sign is one placement among many.

Often confused with

Ascendant: the sign and degree rising on the eastern horizon at birth, which change within hours, where the Sun sign changes about once a month. Moon (astrology): the other luminary; the "moon sign" is the sign the Moon occupied at birth, and since the Moon changes sign every two to three days it often differs from the Sun sign.

In Practice

Once a month for a season, note where the Sun rises on your horizon, standing in the same spot each time. The sunrise point drifts north toward midsummer and south toward midwinter. That yearly swing follows the Sun's path through the zodiac, and the Sun's height in the sky is what Ptolemy used to explain its heat.

Stefan's Alkimia. (2026, September 30). Sun (astrology). Pleroma Guide. https://pleroma.guide/en/lexicon/sun

Stefan's Alkimia. “Sun (astrology).” Pleroma Guide, 30 Sept. 2026, pleroma.guide/en/lexicon/sun.

Stefan's Alkimia. “Sun (astrology).” Pleroma Guide. September 30, 2026. https://pleroma.guide/en/lexicon/sun.

@online{alkimia2026sun,
  author = {{Stefan's Alkimia}},
  title = {{Sun (astrology)}},
  organization = {{Pleroma Guide}},
  date = {2026-09-30},
  year = {2026},
  url = {https://pleroma.guide/en/lexicon/sun},
  langid = {english}
}