Plate VII · the one-ledger orrery
The solar system, in ink and copper
Drag to turn it. Scroll to come closer. Every orbit is drawn from two measured numbers — a distance you can range and a period you can count — and nothing else.
Eight orbits, one length
For every planet the pair (a, T) returns the same length: ϟ = 4π²a³ / T²c² ≈ 1477 m. No gravitational constant and no kilogram enters the computation — click the planets above and watch the last row of the card not move. Standard physics writes this same number GM☉/c²; the orbit ledger cannot discriminate between the two readings. SDT reads it as a length — the Sun's displacement, the koppa — and the depth-closure scroller shows the same 1477 metres read a second way, in the Sun's own spectrum.
The drawing is honest about what it compresses: planet sizes and distances are eased onto one sheet (a true-scale Neptune would put this page forty metres wide), but every shape is real — the eccentricities, the inclinations, and the speeds, with Kepler's equation solved each frame. Mercury visibly hurries at perihelion because it does.