Theoretically, aliens could conquer the earth without firing a shot. All they'd have to do is roll out a few million miles of Reynold's Wrap between us and the sun and just watch us freeze solid within a few months. Then move that massive sun blocker past us and use it as a reflector to warm us back up. There'd still be a few million survivors, but it would surely kill off those 8 billion eaters faster than Voat.