Declination measures the "up-and-down" position of a planet relative to the Celestial Equator. Declination gives planets an added dimension of interpretation (e.g. parallel).
When two planets have the same declination in the same hemisphere (north or south), they are parallel.
Declination uses the Celestial Equator (an extension of Earth's equator out into space) as its baseline measurement. This is similar but completely different from Celestial Latitude which uses the Ecliptic as its baseline measurement.
Pronounced: Dee-klin-NAY-shun or Dek-lin-NAY-shun.
