Solar System Twin

An empty solar system, framed for the outer planets. Extends Astro Twin — read that plate's description for the scale and epoch model this one inherits; what it adds is the framing and the defaults for one subject: bodies on orbits around a star, driven by a clock. celestial.loadSolarSystem builds the Sun, the eight planets, the Moon parented to Earth, and Pluto from bundled JPL Keplerian elements in one call, then frames them. Log scale is the default here and is the reason all nine fit at once: Mercury near 36 scene units, Neptune near 119, the sky sphere at 400, every one of them inside the engine's default 1000-unit far plane so no plate has to manage near/far. Orbit paths are on, and they are drawn from the same elements the bodies are propagated from, so a body travels ALONG its ellipse rather than merely near it — including a moon, whose path uses the same local-slope rule its position does. Saturn and Uranus arrive with their real ring systems; Venus and Uranus with retrograde rotation, carried as a negative period rather than a separate flag; Pluto with the 17-degree inclination that is the reason to include it, and near the perihelion that had it briefly sweeping faster than Neptune around the year 2000. The subject need not be this solar system. celestial.addBody takes its own six Keplerian elements, each as a value at J2000 plus a rate per century, so an exoplanet system, a comet on a long ellipse, or an invented one propagates down exactly the same path — and a body given a `parent` becomes a satellite of it, inheriting the satellite scaling rule. For a twin, the readings that suit this scale are the ones belonging to a fleet rather than to a surface: a probe's health per body, an observatory's pointing, a station-keeping budget. One status LED per body reads a whole fleet at a glance; a gauge plus a trend reads one of them in depth. For surface readings, prefer a single body and 'true' scale, where a marker heat source has a sphere big enough to paint on.