Geometry first
Exact angle, separation, and orb
The exact angle is the ideal geometry for an aspect: 0°, 60°, 90°, 120°, or 180°. Observed angular separation is the smallest distance between the two calculated zodiac longitudes.
Orb difference is the absolute difference between that observed separation and the exact aspect angle. A calculation recognizes the aspect only when the orb difference is within the maximum allowed for its particular context.
What an aspect is not
A relationship, not an actor or location
Planets describe the functions being related. Zodiac signs describe styles of expression. Houses describe life areas or chart contexts.
An aspect describes how two functions connect. It does not replace the planets, signs, houses, or the wider pattern of the chart.
Canonical reference set
Explore all five major aspects
Conjunction
Exact 0°
A conjunction occurs when two chart points occupy the same part of the zodiac, with an exact angular separation of 0°.
Read the full reference →⚹Sextile
Exact 60°
A sextile is a 60° angular relationship between two chart points and is represented by the calculation symbol ⚹.
Read the full reference →□Square
Exact 90°
A square is a 90° angular relationship between two chart points, represented by the symbol □.
Read the full reference →△Trine
Exact 120°
A trine is a 120° angular relationship between two chart points, represented by the symbol △.
Read the full reference →☍Opposition
Exact 180°
An opposition is a 180° angular relationship between two chart points, represented by the symbol ☍.
Read the full reference →How aspects appear
Lines connect the represented chart points
In a chart wheel, aspect lines connect the two supplied endpoints and may use different colours, line treatments, or midpoint glyphs to keep the five relationships distinguishable. Those visual choices present calculated facts; they do not alter the planets' true longitudes, the aspect type, or the orb.
The reference symbol for Sextile is ⚹. The shared interactive chart intentionally uses ✶ as a visual presentation variant. The calculation identity and exact 60° geometry remain unchanged.
Context-specific thresholds
There is no single universal orb here
Different calculations answer different questions, so this repository intentionally uses separate default policies. The exact angle never changes. The maximum accepted difference from that angle depends on whether the calculation concerns planet-to-planet sky or natal geometry, personal transits to a natal chart, or chart-to-chart Synastry.
Current-sky and natal planet aspects
Used by the repository's default planet-to-planet major-aspect calculation, including the natal chart's planetary aspects.
- Conjunction
- ±8°
- Sextile
- ±4°
- Square
- ±6°
- Trine
- ±6°
- Opposition
- ±8°
Personal transit-to-natal aspects
Used when a current transiting planet is compared with a natal planet in the personal transit system.
- Conjunction
- ±3°
- Sextile
- ±2°
- Square
- ±3°
- Trine
- ±3°
- Opposition
- ±3°
Compatibility and Synastry aspects
Used when a supported point in Person A's chart is compared with a supported point in Person B's chart.
- Conjunction
- ±6°
- Sextile
- ±4°
- Square
- ±5°
- Trine
- ±5°
- Opposition
- ±6°
Aspect contexts
Birth Chart
Natal relationships
Natal aspects connect planetary functions at the birth instant. Their meaning belongs within the complete pattern of planets, signs, Placidus houses, and other aspects.
Current sky
Transit geometry
Current-sky aspects describe calculated angular relationships among moving planets. Exact aspect events can also provide timing evidence without making deterministic predictions.
Compatibility
Cross-chart Synastry
Synastry compares supported points across two complete charts. An aspect describes symbolic interaction, not relationship history, quality, destiny, or guaranteed outcomes.