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About the physics & scale →
Orbital mechanics. All bodies follow Keplerian two-body orbits around their primary, computed by solving Kepler's equation E − e·sin E = M via Newton–Raphson each frame. Heliocentric J2000 osculating elements (a, e, i, Ω, ω, M₀) are taken from JPL Solar System Dynamics. Mutual planet–planet perturbations (≪1° per orbit) are not modeled; relativistic precession of Mercury's perihelion (43″/century) is not modeled.
Time. Simulation time advances in days from the J2000.0 epoch (JD 2451545.0 = 2000-01-01 12:00 TT). The "Speed" slider sets days-per-real-second. Orbital periods follow Kepler's third law (T² ∝ a³/M) automatically.
Scale. Distances are true in their relative scale (1 AU = 100 scene units). Body radii are exaggerated by 1500× for planets/moons and 80× for the Sun, so they remain visible at solar-system scale. Toggle True Scale to see the honest 1:1 ratio (Earth becomes ~0.004 units; you must zoom in to see anything).
Reference frame. Scene XZ-plane = J2000 ecliptic; +X to the vernal equinox; +Y to ecliptic north. Orbital inclinations, longitudes of ascending node, and arguments of perihelion are applied in this frame. Moons orbit in their parent's equatorial plane (Laplace plane), with the parent's axial tilt applied.
Galaxy. The Milky Way disc is rendered tilted ~60.2° to the ecliptic (galactic north pole at α=192.86°, δ=27.13°). Nearest stars (Proxima Centauri, Sirius, Barnard's Star, Wolf 359, ε Eridani, τ Ceti) are placed at their true RA/Dec directions on a far sphere — directions are accurate, distances are not (true scale would put α Cen ~28 light-hours of travel beyond Pluto in these units).
Cosmic context. A marker for the CMB dipole apex (the direction the Solar System moves through the cosmic microwave background, l=264°, b=48° galactic) shows our motion through the universe at ~370 km/s.
Known approximations.