Aspect (Astrology)
An aspect is an angular relationship between two planets (or points) in the chart, such as conjunction, opposition, trine, square, sextile.
Aspects are angular relationships between two celestial points (planets, angles, or sensitive points). The main aspects are conjunction (0°), opposition (180°), trine (120°), square (90°), and sextile (60°). Minor aspects (e.g. quincunx 150°) are also used.
Aspects are calculated from ecliptic longitudes; thus they depend on accurate ephemeris data (e.g. Swiss Ephemeris, NASA DE441). Classical astrology emphasized the major aspects and their "harmonic" or "disharmonic" nature; modern astrology adds psychological nuance. Interpreting an aspect involves the planets involved, their signs and houses, and the aspect type.