Semi-square
Two bodies 45° apart, half a square: a minor aspect of irritation and restlessness that keeps a matter moving.
Meaning
A semi-square joins two bodies 45° apart, an eighth of the circle, half a square. It belongs to the square’s family and carries a lighter version of its friction: less a crisis than an itch, a recurring irritation between two functions that never quite settle together.
Forty-five degrees is a sign and a half, so the semi-square follows no rule of signs. Depending on where each body stands in its sign, the two signs are one or two apart, and never share an element or a modality.
It is usually read as a spur. A semi-square seldom dominates a chart, but it keeps a matter from going quiet: small frictions that, once noticed as a pattern, point to something worth adjusting. Its companion at three eighths of the circle, the sesquiquadrate (135°), is read in the same way by those who use it.
In practice
- The Sun semi-square Mars: restlessness and impatience that, given a direction, turn into energy for work.
- Venus semi-square Saturn: affection and caution rub against each other, and closeness comes with small hesitations that patience eases.
- When the same planet also makes squares or oppositions, a semi-square adds to their theme in a lower voice: read it alongside them.
Across traditions
- Cosmobiology, which Reinhold Ebertin built on the 90° dial of the Hamburg School (Kombination der Gestirneinflüsse, 1940), works mainly with the hard aspects, the multiples of 45°. There the semi-square and the sesquiquadrate belong to one family with the conjunction, the square and the opposition.
- Ptolemy’s scheme has no place for it: his configurations join whole signs, and 45° is not a whole number of signs.
How Ulune calculates it
- The semi-square is a minor aspect in Ulune, with an orb of 2°30′, to an angle as well, and 1°30′ in synastry.
- Since it has no fixed count of signs, it is never marked out of sign.
- It is not used in the configurations, and Ulune does not compute the sesquiquadrate.
Correspondences
| Angle | Part of the circle | Signs apart |
|---|---|---|
| 45° | one eighth | one or two |
Related
- AspectA set angle between two bodies of a chart, measured along the zodiac, that astrology reads as a relationship between what they stand for.
- SquareTwo bodies 90° apart, a quarter of the circle: friction that asks for action and, worked with, builds strength.
- Semi-sextileTwo bodies 30° apart, usually in neighbouring signs: a quiet, easily missed link between two very different functions.
- QuintileTwo bodies 72° apart, a fifth of the circle: a minor aspect that modern astrologers link with talent, style and the urge to make.
- OrbThe leeway around an aspect’s exact angle: how far two bodies may stray from it, in degrees, and still count as in aspect.
Sources
- Claudius Ptolemy, Tetrabiblos, c. 150
- Reinhold Ebertin, Kombination der Gestirneinflüsse, 1940