Latitude (Planetary)

Definition

Celestial latitude is how far north or south a planet sits from the ecliptic — the apparent path the Sun traces through the year. It is the second of the two ecliptic coordinates: longitude gives a planet's position along the ecliptic, latitude its offset above or below it. It is separate again from declination, measured from the celestial equator. Each planet's orbit is tilted slightly from the ecliptic — the Moon reaches about 5°09′, Mercury about 7°, Venus about 3°24′, and Pluto, on its steeply tilted orbit, can pass 17°.

In Tradition

Modern Western practice treats celestial latitude as the standard astronomical figure listed next to longitude in Swiss-ephemeris-grade tables. A few practitioners — Robert Hand, Bernadette Brady among them — point out that a high-latitude planet sharing a zodiac degree with another can in fact be far apart in three dimensions, and so they trim the working orb of such conjunctions. Mainstream interpretive practice, though, still uses longitude alone for aspect work.

In Practice

You read latitude straight off any modern ephemeris or chart routine, such as Swiss Ephemeris or astronomy-engine. For most aspect work, longitude alone is enough. Latitude starts to matter when you are doing one of three things. First, computing parallels and contraparallels — aspects on the declination axis, and declination is derived partly from latitude. Second, weighing a conjunction that involves the Moon, Mercury, or an outer planet, where the two bodies can be several degrees apart in latitude even at the same zodiac degree. Third, planning telescope observation, where latitude decides whether a planet is genuinely above the horizon at the longitude you projected. Latitude-aware astrologers sometimes tighten the orb on a high-latitude conjunction for the same reason.

Historical Origin

Celestial latitude appears in Hellenistic astronomy as part of Ptolemy's geocentric model — the Almagest, Books IX-XIII, gives latitude tables for the planets. Bonatti and the medieval Latin tradition pass the concept on with little interpretive use of it. Twentieth-century work — Brown's lunar theory, modern ephemeris computation — sharpens the figures, and latitude returns to interpretive view in the late-20th-century literature on parallel aspects (Hand, Brady).

Etymology

Origin: Latin. Meaning: From latitudo (breadth, width) — the breadth of a planet's deviation from the ecliptic plane.

Definition

In Tradition

In Practice

Historical Origin

Etymology

Further Reading