Separatrix

Three-body physics sandbox

Separatrix is a PC physics sandbox about the three-body problem: the motion of three stars under their gravitational pull. You set each star’s mass, position and velocity, and can adjust how strongly each star pulls. Then you watch the resulting motion. Most starting arrangements end in a collision or send one star away, while stable orbits are rare.

Cataloged orbits

The research archive contains named stable orbits, including Collinear Loop, Equilateral Dance, Figure-Eight Chase and Broucke A1. Some are presented as puzzles: complete a puzzle to unlock its orbit. The catalog also records the author, year and source for its solutions, from the classic work of Euler and Lagrange to later numerical studies by Broucke, Hénon, Šuvakov and Dmitrašinović.