A real gravitational N-body model: planetesimals orbit a young star, feel each other's gravity, and merge on collision — perfectly inelastic, conserving momentum — slowly building a handful of growing protoplanets out of the disk.
💡 Real mechanism: dust grains stick electrostatically, then gravity takes over once clumps reach km scale (runaway accretion). Radius here grows as mass^(1/3) assuming constant density — merges conserve total momentum and total mass exactly (check the readout).
Drag to orbit · Scroll to zoom · Time is compressed millions-fold