Would they just appear or would there be say a streak of light? I am puzzled why, if we are visited, we have not seen ships in the solar system. Do they transition behind a planet or moon then cloak? Which begs the question of why would they hide? At that distance we are no threat. Do they think we would be able to work out the physics of their propulsion? or that it would be destabilizing for us? Or is it nothing to do with us and being uncloaked is intrinsically dangerous?