Orb — Astrology glossary

An orb is the margin of degrees within which an aspect between two planets is considered active. Aspects are defined by exact angles, such as 90 degrees for a square, but planets rarely sit at the precise figure, so astrologers allow a tolerance around it. If a square is exact at 90 degrees and the orb is eight degrees, any separation between 82 and 98 degrees still counts. The smaller the orb, the tighter and stronger the aspect is judged to be; an aspect within one degree is described as exact and treated as especially significant. Orb sizes vary by tradition and by the planets involved, with larger allowances often given to the Sun and Moon. In a natal chart, the orb determines which aspects are counted at all, directly shaping how the planets are read as interacting.