Measure the shorter angle
Subtract one ecliptic longitude from another, wrap the result around the 360° circle, and use the smaller separation from 0° to 180°. A planet at 5° Aries has longitude 5°; a planet at 8° Cancer has longitude 98°. Their shorter separation is 93°, three degrees from an exact 90° square. The positions and the difference can be checked independently of any interpretation. A chart should display the measured orb instead of merely stamping an aspect name on the pair.
Five common aspect families
Conjunction is centered on 0°, sextile on 60°, square on 90°, trine on 120°, and opposition on 180°. Some traditions use other divisions of the circle, including quincunxes or minor harmonic aspects. Adding many aspect types can make almost every pair appear connected, so the chosen set should be stated. A wide-orb square and a narrow-orb square are not equally close geometrically. If an aspect list changes between sites, check the aspect family and allowable orb before assuming an astronomical error.
The orb is a declared tolerance
An orb is the distance from exactness that a calculator permits. For the 93° separation above, the square has a 3° orb. A 2° maximum would omit it; a 5° maximum would include it. Some methods vary limits by planet or aspect, while others use one simple rule. Check the allowed orb when comparing charts. Orb choices influence how dense a chart looks, but no threshold proves that a particular relationship or event will occur.
Read the pair, not just the symbol
The aspect symbol is a prompt to compare two distinct planetary roles. Ask whether the pair is natal or a transit-to-natal comparison, whether an angle depends on uncertain birth time, and whether an applying or separating distinction is actually supported by the data shown. A transit aspect may have more than one exact crossing when a planet stations and reverses apparent direction. A dated calendar should show those crossings rather than promise one decisive day. Interpretation remains contextual and contestable even when the geometry is exact.
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Updated 20 September 2026