Orb

An orb is the maximum angular distance from an exact aspect within which the aspect is still considered operative. For example, if a trine is defined as exactly 120°, a planet at 118° or 123° from another planet is still within the trine's orb. William Lilly (Christian Astrology, 1647, p. 107) described precise orb allowances for each planet — the Sun was granted a wide orb of approximately 15°, while Saturn and Mars were granted around 9°, and the Moon up to 12°. Lilly called the zone of influence around a planet its moiety — half of each planet's total orb assigned to that body individually. In practice this means a Sun-Jupiter trine is considered orb-wide up to the sum of both planets' moieties. Modern practice has simplified this: most contemporary astrologers use fixed orbs by aspect type rather than by planet, with conjunctions and oppositions typically granted 8°–10°, trines and squares 6°–8°, and sextiles 4°–6°. Robert Hand (Horoscope Symbols, 1981) emphasized that orb is not a binary on/off but a gradient — a 1° orb conjunction is far more powerful than a 9° orb conjunction, even if both technically count. For fixed stars, traditional orb is a tight 1° (Brady, Brady's Book of Fixed Stars, 1998).