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”
These are 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.