Transit Duration

Definition

Transit duration is the length of time a transiting planet remains in contact with a natal point — either by being within orb of an aspect or, in the Hellenistic zoidion-based system, by occupying a given sign. Duration varies dramatically by planet because the planets move at very different speeds: the Moon spends only about two and a half days per sign, while Saturn requires about two and a half years to cross one sign.

In Tradition

Across the Hellenistic tradition and its modern revival, transit duration is read as a fundamental parameter for predictive weighting: slower-moving transits are more durable and significant in their effects, while faster-moving transits are more episodic and short-lived. Crane gives the per-planet figures plainly — Saturn ~2.5 years per sign, Jupiter ~1 year, Mars 2 months (or up to half a year retrograde), Sun 1 month, Venus and Mercury under a month, Moon 2.5 days.

In Practice

Practitioners use transit duration in three classical contexts. First, in weighting: a transit of Saturn or Jupiter across a natal angle or to a natal planet carries more predictive weight than a fast Moon or Mercury transit, both because the contact is sustained for weeks or months rather than hours, and because the slower planet's significations tend toward structural change rather than fleeting mood. Second, in timing windows: retrograde stations and direct stations extend a slow-planet transit into three-pass contact (direct-retrograde-direct), so that, for instance, a Saturn transit over a natal Sun may be live for over a year across the three exact contacts. Third, in event-charting: faster transits supply the trigger for slow-transit themes — the Moon or inner planets activating a natal point already under Jupiter or Saturn transit often coincide with concrete events crystallizing the longer process.

Historical Origin

Transit doctrine is documented in the Hellenistic tradition (Valens, Dorotheus) on a zoidion-based framework where transits are evaluated by sign-ingress rather than by point-to-point aspect. Crane's *Astrological Roots: The Hellenistic Legacy* (2007) preserves the per-planet duration table on pp. 525-529 within the zoidion-based transit doctrine. Modern Western practice extends the framework to include orb-based aspect duration, with Hand's *Planets in Transit* (1976) as a widely used reference for orb-modulated transit timing.

Definition

In Tradition

In Practice

Historical Origin

Further Reading