Orrery / first principles

N-body gravitation · eclipse prediction

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simulation time (UTC)

The physics

aᵢ = Σⱼ G mⱼ (rⱼ−rᵢ) / |rⱼ−rᵢ|³

integratorvelocity Verlet

bodies / pairs10 / 45

time step600 s

energy drift |ΔE/E|0

Initial state at t₀ from orbital elements + lunar series; everything after is pure Newton. No ephemeris lookups — eclipses emerge from gravity. Minor moons ride Kepler rails about their parents (display layer only).

drag to orbit · scroll to zoom · click any body for a close-up · double-click to reset

Eclipse prediction

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View

planet size

moon size

moons orbits labels

sizes & moon orbits exaggerated for visibility — positions stay physical

view from shadow centre

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obscuration — shadow centre — γ — —

A connection is required once

to fetch the Three.js rendering library (the physics runs locally).