Equal distance across the equator
Imagine Venus at 12.6° north and Mars at 12.1° south. Their distances from the celestial equator differ by 0.5°, so they are contra-parallel under a 1° orb. The formula for opposite signs is |δ₁ + δ₂|. The signs matter: Venus at 12.6° N and Mars at 12.1° N would be a parallel instead. The table keeps N and S visible so a reader can check each label.
Contra-parallel does not mean the bodies stand 180° apart in zodiac longitude or right ascension. It describes mirrored declination, a single north–south coordinate. Nor does it mean the bodies are nearest each other in the sky. A broad astrological shorthand compares the contra-parallel to an opposition, but the measured geometry and that symbolic interpretation are different claims.
Check the Moon and the date
The Moon can change declination noticeably within a local day. If only the birth date is known, a noon chart can suggest a north–south pairing that was absent at another hour. The date-only calculator samples the day and labels any matches as possible. It does not manufacture a precise natal time or replace a recorded UTC offset with a guessed time zone. Close results should be recalculated when the record is found.
A different use of “parallel”
Declination parallels and mundane parallels measured relative to meridian or horizon positions use different coordinates and cannot be substituted for one another. This tool reports only declination parallels and contra-parallels among the ten listed bodies, with an adjustable 0.25°–1.3° orb.