Phasis

FAY-sis

Definition

Phasis is a planet's phase in relation to the Sun — where it sits in the cycle of becoming visible and then disappearing again. The Greek phasis (φάσις, "appearance, phase") covers the moments when a planet emerges from the Sun's glare after being hidden (its heliacal rising) and when it sinks back into invisibility before being swallowed by the Sun (its heliacal setting). Late Babylonian astronomers laid these stations out as the Greek-letter phenomena: for the outer planets, Γ (first visibility in the east), Φ (first station), Θ (acronychal rising), Ψ (second station), and Ω (last visibility), with matching sequences for the inner planets.

In Tradition

In Hellenistic and later Arabic-mediated traditional astrology, phasis is its own kind of planetary condition — separate from sign, house, and aspect. It is a Sun-relative status that changes a planet's ability to act. A planet emerging from the Sun's rays into first visibility reads as powerfully switched on; one sinking under the rays, as weakened. Dorotheus, in the Arabic transmission, weighs the Lord of the Year's phasis — combust or under the rays, versus emerging and direct — when judging the year ahead.

In Practice

You assess phasis by looking at how far a planet stands from the Sun (its elongation), which way it is moving (direct or retrograde), and where it is relative to its inferior or superior conjunction. The standard categories are: under the rays — within roughly 15 to 17 degrees of the Sun, depending on the planet and the authority; heliacal rising — first visibility after coming out of inferior conjunction; heliacal setting — last visibility before being swallowed; morning star (oriental), rising ahead of the Sun; and evening star (occidental), setting after it. The old Babylonian observers tied phasis to omen reading; Hellenistic and Arabic natal astrology carried it forward instead as a condition weighed alongside dignity and aspect. In timing work today, the heliacal rising of an outer planet is still a recognised station.

Historical Origin

The framework of these synodic phenomena, with its Greek-letter conventions, was worked out by Late Babylonian astronomers and set down for modern study by Otto Neugebauer; Hunger and Pingree document it in *Astral Sciences in Mesopotamia*. The Greek phasis appears in the Hellenistic technical literature — Lightfoot notes its use in the Pseudo-Manetho Apotelesmatica. Dorotheus of Sidon's Book IV uses the Arabic calque asas (أساس, "foundation") for phasis, a transliteration Dykes's footnote identifies. The doctrine passed through Persian and Arabic intermediaries into medieval Latin practice.

Definition

In Tradition

In Practice

Historical Origin

Further Reading