Orbit Simulator

Choose an illustrative scene, then Run or Step. Restart restarts the current initial conditions and keeps your custom bodies. The central mass stays fixed; orbiters feel its gravity only. Their own masses do not change the trajectories, and they do not attract each other. These presets are ideal planar examples, not ephemerides.

Under Edit initial conditions, set positions in km, velocities in km/s, and masses in kg. Select the body to inspect in Focus orbiter. The preview and canvas fit the actual orbital scale. Dot sizes and velocity arrow lengths are schematic. The orbit details describe the current osculating conic.

Velocity-Verlet integrates your Δt. Steps per frame controls playback and depends on the display frame rate. Large steps are rejected using a conservative local dynamical/crossing-time guard; this is not an accuracy guarantee. Reduce Δt to inspect convergence. Radial fall into the singular point centre is unsupported; there are no finite surfaces, collisions, relativistic effects or external perturbations.

Area sectors approximate equal-time sweeps with sampled chords: each boundary is rounded to an integration step. The displayed areas therefore have discretization error. Closer to periapsis the body moves faster; the exact area rate remains constant. Pausing or hiding the page stops computation. The trail is bounded to 1200 samples.