Orb
The leeway around an aspect’s exact angle: how far two bodies may stray from it, in degrees, and still count as in aspect.
Meaning
Two bodies seldom stand at an exact angle. Venus may be 117° from Mars rather than 120°, and most astrologers still call that a trine, three degrees from exact. The orb names both sides of this: the margin an aspect is allowed (a trine may be given 8°), and how far a particular aspect is from exact (this trine has an orb of 3°).
The usual rule is that the closer to exact, the stronger the aspect. A contact within a degree is read as a defining trait; one near the edge of its orb as a background note. An exact aspect is rare and striking, while a wide one is still a thread, only a thinner one.
Orbs are a convention, not a measurement. Astrologers broadly agree that the major aspects deserve more room than the minor ones, and the conjunction and the opposition the most, but the numbers vary from school to school: from about 6° to 10° for a conjunction, from 1° to 3° for a minor aspect, often a little more when the Sun or the Moon is involved. A narrow orb keeps fewer, stronger aspects; a wide one finds more connections at the price of noise. No setting is the true one; what matters is knowing which one a chart was read with.
There are two ways of thinking about it. Most modern astrology gives the orb to the aspect: so many degrees for a trine, fewer for a sextile. Older astrology gave it to the planet: each body shone with a sphere of light of its own, wider for the Sun and the Moon, and two planets were joined when their spheres met.
In practice
- Venus at 10° Taurus and Mars at 15° Virgo are 125° apart: a trine with an orb of 5°. Move Mars to 20° Virgo and they are 130° apart, 10° from exact; most astrologers would no longer count a trine.
- Read the tightest aspects first. A list sorted by orb is a fair first ranking of what stands out in a chart.
- Orb and motion go together: an aspect 3° from exact and applying is still gathering; at the same orb but separating, it is fading.
- In a transit, the orb becomes time. A slow planet can stay within a degree of an exact aspect to the birth chart for weeks or months, the span Ulune calls a window.
- An orb can carry an aspect across the border between two signs, so that the degrees make an aspect the signs do not: an out-of-sign aspect.
Origin and history
Traditional astrology measured orbs by planet. In Christian Astrology (1647), William Lilly gives his table: 15° for the Sun, 12° for the Moon, 9° for Saturn and Jupiter, 7° for Mars, Venus and Mercury. Two planets were in aspect when the distance from exact fell within half of their two orbs added together, their moieties: for the Moon and Saturn, 12° and 9° make 21°, so 10°30′.
Lilly also distinguished a partile aspect, with both planets at the same degree of their signs (Venus at 9° Aries and Jupiter at 9° Leo make a partile trine), from a platic one, within orb but not exact to the degree. Most modern astrology, and most astrology software, Ulune included, sets orbs by aspect instead of by planet.
How Ulune calculates it
Ulune casts a birth chart with these orbs:
| Aspect | Orb | To an angle |
|---|---|---|
| Conjunction, opposition, square | 8° | 8° |
| Trine | 8° | 6° |
| Sextile | 6° | 4° |
| Quincunx | 3° | 3° |
| Semi-sextile, semi-square | 2°30′ | 2°30′ |
| Quintile | 2° | 2° |
- “To an angle” means an aspect to the Ascendant, the Descendant, the Midheaven or the IC. The cast gives no extra orb to the Sun or the Moon.
- The orb shown is the distance from exact, in degrees and minutes. The Table sets it beside the orb allowed (“1°12′ of 8°”) with a bar for its strength, full when exact and empty at the edge of the orb, and can keep only the aspects within 3° or within 1°.
- The wheel draws fewer lines than the Table lists. Its views set a limit: the conjunction, opposition, square and trine within 3° in Minimal, the five majors within 5° in Classic (the default), all nine aspects within 6° in Advanced, the full orbs in All. Under Bodies, then Aspects, a Max orb slider runs from ½° to 8°, each aspect can be given an orb of its own, and a box gives the Sun and the Moon 2° more. These settings only narrow what is drawn: no line is ever wider than the orbs in the table above.
- Transits and progressions to the birth chart use the same orbs, and their tables list the major aspects. Synastry uses tighter ones: 6° for the conjunction, opposition, square and trine and 4° for the sextile, a degree more for these when the Sun or the Moon is involved; 2° for the quincunx and 1°30′ for the other minor aspects; never wider than the birth chart’s own orb for that pair.
- Without a birth time, an aspect that may leave its orb, or become exact, at another hour of the day is marked ~.
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.
- ExactThe minute an aspect or a crossing is precise to the degree, minute and second, the peak of a transit.
- Applying and separatingWhether an aspect is still forming, its two bodies closing on the exact angle, or already passing, the gap between them widening again.
- Out-of-sign aspectAn aspect the degrees make but the signs do not, such as a trine from the last degree of Aries to the first of Virgo.
- ConjunctionTwo bodies at the same place in the zodiac, 0° apart, their meanings fused into one strong theme.
- Transit windowThe weeks or months a slow planet stays within 1° of an exact aspect to a chart, which a retrograde can make exact two or three times.
Sources
- William Lilly, Christian Astrology, 1647