Reference · Astrology
What is a quincunx?
Kevin Blaxton — software builder; astrology student for 40+ years · figures computed by the OrbHeaven engine
Published · Last revised
A quincunx, also called the inconjunct, is the aspect of 150°: two planets five signs apart, in signs that share neither element nor mode and so have nothing obvious in common. It is not one of the aspects Ptolemy used, astrologers differ on whether to count it at all, and OrbHeaven gives it the tightest orb of any aspect it tracks.
What is a quincunx?
Geometrically it is an aspect of 150° — two planets five signs apart in ecliptic longitude. Signs five apart share neither element nor modality, so unlike the trine or square there is no structural affinity between them; the quincunx joins two signs that, in the old language, “cannot see each other”.
How it is counted: the orb
An exact quincunx is 150°. OrbHeaven counts one only within 2.5° of that in a birth chart, or 3.5° when the Sun or Moon is involved — by far the tightest orb it allows, reflecting that the quincunx is treated as a weak, minor aspect. The figure shows the 150° angle and that narrow margin.
What it is read as
Interpretation, labelled as such: the quincunx is read as an awkward fit — two planets that do not naturally combine and must be adjusted to each other, often described as a persistent need to tweak or accommodate. It is a minor aspect, and some astrologers weight it lightly or not at all.
Where this is disputed
Whether the quincunx should be counted is a genuine, open disagreement. It is not a Ptolemaic aspect, its orb and even its validity vary by practitioner, and some traditions ignore it entirely. OrbHeaven includes it with a deliberately tight orb and flags the dispute rather than settling it.
A short history
The 150° relation was known in antiquity as “inconjunct” — signs that are not configured with one another at all, precisely because they are not joined by any of Ptolemy’s four angular aspects. Counting it as an active aspect is a later, mostly modern development. The wider idea of “minor aspects” grew from the seventeenth century on — Kepler, in Harmonices Mundi (1619), added several on harmonic grounds — but the quincunx’s rehabilitation in particular is largely a twentieth-century one, which is why its status is still unsettled.
Common misconceptions
- Is the quincunx one of the main aspects?
- No. It is a minor aspect and not one of Ptolemy’s configurations. Astrologers disagree on whether to count it, and OrbHeaven gives it the tightest orb of any aspect it tracks.
- What is the difference between a quincunx and an inconjunct?
- They are the same 150° aspect. “Inconjunct” is the older term, from the idea that signs 150° apart are not configured with — cannot “see” — each other.
References & further reading
- [1] Ptolemy, Tetrabiblos (2nd c. CE) — the four angular aspects, from which the 150° relation is excluded (inconjunct).
- [2] Kepler, J., Harmonices Mundi (1619) — the harmonic introduction of “minor” aspects beyond the four Ptolemaic configurations (chiefly the quintile family; the quincunx’s later status is modern).
- [3] OrbHeaven engine (astronomy-engine), aspects module — the 150° angle and the 2.5°/3.5° natal orb; re-derived in aspects-demo.test.ts.
Suggested citation
Blaxton, K. (2026). What is a quincunx. OrbHeaven Reference. https://orbheaven.com/reference/the-quincunxRevision history
- First build (concise). Shared aspect-shape diagram (150°, engine orb — the tightest); links up to the Aspects hub and Orbs. Flags the real dispute over whether to count it; its non-Ptolemaic origin given as history. Geometry, orb computation, tradition and history kept separate. No interactive.
About a minute. Birth time optional, and no account until after you have seen it.
More in the reference library
What is an aspect in astrology? The angles, the orbs, and the geometry
An aspect is the angle between two points in a chart. This is the geometry — the six angles astrologers use, what an orb is, and where the set comes from — with an interactive dial that classifies any separation using OrbHeaven’s engine.
What is an orb in astrology?
An orb is how far an aspect is from exact — and how far from exact still counts. This explains the arithmetic, OrbHeaven’s orb table and the luminary rule, with an interactive dial, and that orbs are a convention of practice, not a scientific threshold.
What are the twelve signs of the zodiac?
The twelve signs are equal 30° slices of the ecliptic, sorted by four elements and three modalities. This explains the structure, how a sign is determined, why the signs are not the constellations they are named for, and what the tradition reads into them.