Western astrology guide
Astrology aspects, exact angles, and orbs
An aspect is an angular relationship between two chart points; its interpretation should remain connected to the exact geometry.
Western Birth Chart · 9 minute read
Written and reviewed by ReadAstrology Editorial & Calculation Team. Published 2026-07-18T00:00:00-05:00. Modified 2026-07-18T00:00:00-05:00.
Key takeaways
- Aspects are measured from exact angular separation.
- Orb rules must be disclosed because traditions differ.
- Applying or separating motion requires speed and direction data.
Methodology: The Show the Math layer records both the exact separation and orb used to classify each aspect.
Astrology and numerology are cultural and symbolic traditions, not scientifically validated methods for predicting events, diagnosing conditions, or guaranteeing outcomes.
Sources and calculation references
- Swiss Ephemeris General Documentation — Astrodienst AG. Planetary, lunar, house, aspect, and coordinate calculation background.
- Orbits and Ephemerides — NASA Jet Propulsion Laboratory. Definition and role of ephemerides and solar-system position data.
How an aspect is measured
Take the absolute difference between two ecliptic longitudes and reduce it to the shortest angle from 0 to 180 degrees. Compare that separation with a target aspect angle.
The orb is the absolute difference between the measured separation and the exact aspect. Smaller orbs are generally treated as stronger within the chosen rules.
The five major aspects
A conjunction targets 0 degrees, sextile 60, square 90, trine 120, and opposition 180. Astrological traditions assign different symbolic qualities to these geometries.
The geometry is objective within the chart settings; labels such as harmonious or challenging are interpretive conventions.
Choosing aspect orbs
There is no single universal orb table. Astrologers may vary orbs by aspect, planet, luminary, or application. Software should publish its thresholds instead of presenting them as hidden rules.
A 92-degree separation is a square with a 2-degree orb. A 100-degree separation may not qualify if the allowed square orb is narrower than 10 degrees.
Applying and separating aspects
An applying aspect is moving toward exactness; a separating aspect has already passed exactness. Determining this requires planetary speed and direction, not only static longitudes.
Applying or separating status can refine timing-oriented interpretations but should not replace the basic orb and chart context.
Frequently asked questions
What is an orb in astrology?
An orb is the difference between the actual angular separation of two points and the exact angle of an aspect.
Which astrology aspect is strongest?
Strength depends on orb, planets involved, angularity, applying or separating motion, and the interpretive system. An exact aspect is geometrically strongest.
Can two planets have more than one major aspect?
For a single pair at one moment, the shortest angular separation normally matches at most one major aspect within standard orb limits.