How are station, retrograde, and direct motion determined?
The labels come from the sign and near-zero behavior of a declared apparent longitude speed. A station is a root or bounded minimum near the change of direction, not an indefinitely precise instant independent of tolerance. The calculation must preserve ephemeris, frame, speed definition, search interval, and uncertainty.
Direct answer
The labels come from the sign and near-zero behavior of a declared apparent longitude speed. A station is a root or bounded minimum near the change of direction, not an indefinitely precise instant independent of tolerance. The calculation must preserve ephemeris, frame, speed definition, search interval, and uncertainty.
Practical use
What to do with this answer
Report the root-finding tolerance and distinguish a numerical station instant from a broader interpretive “station period.” Search both sides of the root to confirm the direction change.
Distinctions to preserve
- Apparent longitude speed versus physical orbital reversal
- Numerical station instant versus interpretive window
- Root tolerance versus display precision
Limitations
- Different coordinate definitions can move the reported instant slightly.
- The motion label alone supplies no predictive meaning.
Authority graph
Which existing contracts carry the answer
These linked pages carry the underlying definition, method, or tradition record and its own sources. This page preserves their boundaries rather than becoming a new source of independent authority.
Retrograde, station, and direct-motion labels →
Establishes: Retrograde and direct describe the sign of apparent longitudinal motion; stationary is a thresholded label around zero speed.
Boundary: Retrograde motion is apparent geometry and does not by itself imply delays, reversals, or outcomes.
Mercury direct and retrograde station reference →
Establishes: A Mercury station is the instant at which the time derivative of its unwrapped apparent geocentric ecliptic longitude changes sign. “Stationary” names a coordinate extremum; the body does not stop moving through physical space.
Boundary: A Mercury station does not establish that plans reverse, decisions fail, communications change, or any future event becomes more or less likely.
Retrograde motion and repeated boundary crossings →
Establishes: Stations and reversals describe the same planetary motion in both zodiac frames, although a station can fall inside differently named signs.
Boundary: Do not call the first, final, or closest crossing uniquely operative unless that selection policy was declared before the target outcome.
Equivalent questions
These query forms resolve to this same answer identity; they are not separate claims.
- How is Mercury retrograde calculated?
- What is a planetary station?
- Does a planet actually move backward?
- How precise is a station time?
Non-claim
This answer is a method or tradition description. It is not a personalized reading and does not certify predictive validity, causation, medical outcomes, legal status, investment value, or guaranteed events.