Arc

Definition

An arc is a measured portion of a circle, expressed in degrees, minutes, and seconds. In astrology, it usually describes the angular distance between two points on the zodiac, celestial sphere, or another relevant circle. The term can refer to a simple separation or to a calculated distance used in predictive techniques.

Astrological Meaning

The meaning of an arc depends on the method in which it appears. An aspect may be identified by the arc separating two planets, such as approximately 120 degrees for a trine. In primary directions, an arc of direction is derived from the apparent movement of the celestial sphere and then converted symbolically into time. In solar arc directions, every point in the natal chart is advanced by the same arc, based on the Sun’s secondary progressed motion. These arcs are then compared with natal positions to identify periods when particular chart themes may become more noticeable.

Why It Matters

Understanding arcs helps distinguish actual planetary motion from symbolic measurement. This is especially important when reading traditional timing methods or solar arc directions, because each system calculates and interprets distance differently. An arc does not guarantee an event; it provides a structured way to examine angular relationships, timing indicators, and developing themes alongside the natal chart and other astrological factors.

Related Encyclopedia Entries

• Traditional Astrology
• Astrological Terminology
• Natal Chart
• Primary Directions
• Solar Arc Directions
• Aspects