Calculation and reading limits
Both views plot apparent geocentric tropical longitude for Mars, Jupiter, Saturn, Uranus, Neptune, and Pluto. The five-year view calculates a point every UTC day. The fifty-year view calculates a point every seven UTC days so the broader pattern remains manageable in a browser. Lines break at the Pisces–Aries wrap rather than drawing a false leap across the chart.
The curves show sampled positions, not exact station times. A bend may suggest a retrograde period; use the one-year graph or station calendar to inspect that period. The position table is independently calculated on each month's first day in the five-year view, or each year's first day in the fifty-year view, plus the chosen start. The downloadable CSV contains those dates and unrounded decimal longitudes.
All positions come from Astronomy Engine 2.1.19 using apparent geocentric vectors and the true ecliptic of date. No natal overlay, house, location, Chiron, or asteroid positions appear here.