Orb

orb

Definition

The orb is how much room an aspect has to be off from exact and still count. An aspect is strongest when it is exact — astrologers call that partile — and grows weaker as the two planets drift away from the precise angle. There is no single agreed figure: orb values differ from one tradition and one astrologer to the next.

In Tradition

Western astrologers generally allow a wider orb for the major aspects than for the minor ones. The Sun and Moon are traditionally given wider orbs than the other planets, because of how prominent they are.

In Practice

Astrologers use the orb to decide which aspects are live. There are two main approaches: a fixed orb set per aspect type, and the older moiety system, in which each planet carries its own half-orb. The tightest aspects — within 1° of exact — are read as the most powerful. And an applying aspect, one still building toward exact, is generally treated as stronger than a separating one moving away from it.

Historical Origin

The idea has ancient roots in the moiety system, where each planet was given a sphere of influence based on how brightly it shone. Assigning orbs to aspect types rather than to planets came later — it is attributed to Alan Leo in the early 20th century.

Definition

In Tradition

In Practice

Historical Origin

Further Reading