Woking (sort of)

src/Body.java

@@ -39,6 +39,7 @@ public class Body {
     public Vector gravitationalForce(Body b) {
         Vector direction = b.massCenter.minus(massCenter);
         double distance = direction.length();
+        if (distance == 0) return new Vector();
         direction.normalize();
         double force = Simulation.G * mass * b.mass / (distance * distance);
         return direction.times(force);