Spiral Galaxy Simulator (2D)

This 2D top-down simulator renders a spiral galaxy as thousands of stars orbiting a bright core under a real galactic rotation curve — flat circular speed with radius, the same law astronomers use as evidence for dark matter — rather than Keplerian falloff. Tune the star count, arm count, initial pitch angle and random scatter to reshape the disk, then watch differential rotation wind the arms tighter over time as the live readout tracks elapsed time, the orbital period at the core versus the edge, and the edge's steady orbital speed.