UNBOUND
E Vaibhavi Tej
Watch gravity alone decide a planet's fate as a rogue star tears through its solar system.
What it does
Unbound is a real-time 2D N-body gravitational simulation. A host star with two planets sits in stable orbit until a compact rogue star flies through the system and from that point on, nothing is scripted. Every trajectory is the result of Newtonian gravity summed frame-by-frame with a symplectic Velocity Verlet integrator, the same class of method used for real orbital mechanics.
Each planet's specific orbital energy (E = v²/2 − GM/r) is tracked live to determine whether it stays bound, shifts into a new eccentric orbit, or becomes unbound and escapes the outcome depends entirely on the encounter's geometry and speed, not a predetermined animation.
The hardest part wasn't the gravity itself it was proving the simulation could be trusted near the close encounter, where force spikes and integration error are easy to hide. I ran a timestep convergence test (comparing dt and dt/2 on an identical flyby) and confirmed energy values agreed to within ~0.06%, meaning the disruption you see is real physics, not a numerical artifact.
This is a synthetic Newtonian model. It excludes general relativity, stellar evolution, and hydrodynamics. The rogue object is represented as a gravitational point mass, and visual sizes are enlarged for clarity.