"""Solar system: the four inner planets running Kepler ellipses round the sun.
Every planet is solved from Kepler's equation rather than integrated, for the
same reason as orbit_ellipse.py: an integrated orbit never quite closes and a
loop that does not close has a seam. It also hands each planet its own speed
along its own ellipse for free, fast through perihelion and slow at aphelion.
The loop is seamless because every planet makes a whole number of laps in the
eight seconds. The laps are 8, 3, 2 and 1, which keeps the real ordering of
the periods (Mercury about four Earth years to one, Venus about one and a half,
Mars about half) without any planet finishing a fractional turn.
Two of the catalog's toggles are not layers. `speed` is the player's playback
rate and `distscale` swaps the whole geometry between true and compressed
distances, which is a second body rather than something to composite over the
first, so neither ships a PNG. The compressed scale is the one drawn: at true
The full Manim source and the rendered video come with a plan.
