Motion belongs to a coordinate frame
Swiss Ephemeris distinguishes coordinate frames and apparent positions. A longitude and its rate of change must be read in the same declared frame. A negative ecliptic-longitude speed is a decreasing coordinate; it does not mean that a planet reverses its physical orbit.
How the profection report labels natal motion
The Atlas annual-profection tool reads the selected ruler’s natal tropical, geocentric longitude speed in degrees per day. A negative finite value is Retrograde; a positive finite value is Direct. Exactly zero is displayed as Zero instantaneous longitude speed. There is no tolerance band that relabels small nonzero values as stationary.
This label describes the natal calculation supplied to the report. Changing the completed age can select a different annual ruler; it does not move that ruler forward to a new date or calculate its current transit.
Worked example · separate the role from the motion
Use an invented chart with Taurus rising at 45° ecliptic longitude and completed age 0. The annual ruler is Venus. If its supplied natal longitude is 80° and speed is −0.01° per day, the tool reports Venus in Gemini, whole-sign house two, Retrograde.
Keep the longitude unchanged and replace only the synthetic speed with +0.01° per day. The annual ruler, sign and house stay the same; the motion label becomes Direct. These are artificial inputs for explaining the rule, not two measured planetary positions or a prediction.
Zero, missing and a station are different statements
A missing or non-finite speed is Unavailable, even when the natal longitude exists. If the natal longitude itself is unavailable, the tool omits the ruler’s natal placement interpretation. It does not fill either gap with a current ephemeris value.
An exact zero value in a supplied record is an instantaneous result. Finding a station event would require a separate search through time with its own method and accuracy statement. This annual tool does not perform that search or infer a station date from a rounded displayed number.
Interpretation requires a named method
The profection report uses house topics for its attributed reading and shows the natal motion as a fact. It does not assign a favorable or unfavorable outcome from Retrograde or Direct. Tradition-specific judgements about motion belong to their own rules and context.
When revisiting a saved report, compare its captured settings, input speeds and interpretation rather than assuming a present-day calculation. A new calculation should be saved separately when you intentionally change the underlying birth data.
Word origin · etymology
Latin through Middle English.
Retrogradus means going backward, from retro- and gradi, to step or go. The chart usage describes apparent backward longitude motion.
How we know · epistemology
Apparent motion in a reference frame
Successive positions establish whether longitude is increasing or decreasing in the declared frame. In a geocentric chart this can be an apparent reversal produced by relative motion and viewpoint. Traditional horary associations such as delay, return, or reversal are interpretive and require the rest of the selected method; they are not measured consequences of the motion.
Swiss Ephemeris: technical documentation ↗William Lilly: Christian Astrology, original p.115 · accidental fortitudes ↗
Explore it in your atlas
Connected concepts
Read alongside this entry
Terms used in this explanation
Mentioned in 4 other entries
These links connect subjects and terminology. They do not establish a shared historical origin.
Sources & provenance
Use the citations beside each section to distinguish a calculation convention, a historical teaching and an editorial example.