An expert on alien spacecraft, former head of the US military's special department for UFO research, taught how to distinguish alien spacecraft from human-made spacecraft. Luis Elizondo shared the US military experience on this issue.
According to Luis, alien ships can be recognized almost immediately, as they are very different from terrestrial spacecraft. For example, terrestrial spaceships cannot move like UFOs, cannot accelerate quickly, or hover in the air. Among other things, alien ships move almost silently, but terrestrial spacecraft do not.
Although, alien spaceships cannot be classified according to any criteria, since they all differ greatly from each other in shape, size and appearance. Another difference between alien starships is the fact that they move freely through the air, in water, in space. They are not affected by Earth's gravity.
Earth scientists have long been arguing about whether aliens exist, but people around the world are increasingly witnessing the arrival of aliens from other worlds to our planet.