Word origin · etymology
Descriptive English phrase with Latin-derived vocabulary.
Stationary belongs to Latin statio, a standing; direct comes from directus, straight. The qualifier names the direction resumed after the apparent pause.
How we know · epistemology
Computed apparent-motion event
A root of longitude speed is classified by motion on both sides. Its time depends on the coordinate convention; it is not a physical restart or an automatic improvement in circumstances.
Swiss Ephemeris: Programming Interface, position and speed ↗NASA StarChild: What does Mercury in retrograde mean? ↗
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