Construction and correction notes
The source uses “tangent” to describe ellipse orientation along an orbit; several ellipses are centered on the orbit and therefore intersect it rather than touch it at a single point. This gallery preserves those supplied constructions instead of silently replacing their geometry.
Each document runs in its own iframe, isolating canvas IDs, variables, styles and animation loops. Switching studies replaces the previous document. Motion is paced at a fixed 60-step reference rate, independent of display refresh rate. Pause, PNG export and standalone HTML export operate on the selected study. Reduced-motion preferences start paused.