int numShipsToSend = origin.getNumShips() - numShipsToLeaveBehind;
List<Planet> planets = Galaxy.getPlanets();
// we must set a comparator to sort all the planets relative to.
Collections.sort(planets, new PlanetComparator(origin));
// find the numAttack closest planets
List<Planet> closestEnemies = new ArrayList<Planet>();
Iterator it = planets.iterator();
int ct = 0;