That question brings us to the next point which is that alien doesn't necessitate ET. The concept of being alien applies to any given context whereby boundaries are juxtaposed by something foreign. For example the so-called "illegal aliens" aren't ETs, they're just people from another country. It can also be used to describe the invasion of foreign organisms into an ecosystem or body. In the case of UFOs, It means alien to our modern global civilization. There is some evidence that they have been tracked in space, but that doesn't necessitate that space is their ultimate origin. It may be that the aliens are from some as of yet undiscovered terrestrial location, or perhaps even an alternate universe, or are transports from Hell, but I ask you, when we consider those alternatives and compare them to the standard ETH, which seems the most reasonable? Which has the most proven science behind it? There is no evidence on Earth of the resource extraction, infrastructure and manufacturing facilities that would be needed to construct UFOs, especially the very large ones, the other ETH ( Extratemporal Hypothesis ) simply doesn't make any sense, neither does the EDH ( Extradimensional Hypothesis ), and the AUH ( Alternate Universe Hypothesis ), although possible, requires completely unproven and complex assumptions. On the other hand science has proven that other planets exist in the universe and that space is navigable. There is nothing unscientific about interstellar travel, and given sheer the number of stars and planets, it's a virtual certainty that other sufficiently advanced life exists in our universe. Of all the theories, the standard ETH remains the most scientifically reasonable explanation.
Those are perfectly valid points. Although we know UFOs are alien craft, their ultimate point of origin has not been proven ( at least not to the public ). Exactly how they work, where they originate, and why they are here, are all questions for which insufficient evidence exists to draw any certain and detailed conclusions. But that still doesn't mean we don't know what they are. As I pointed out before, we may see a car at some distance on the highway, and we may not know its make or model or where it was manufactured, or who is driving it. But we still know it's a car and we define it by what it is ... not what it isn't. We don't suddenly call it an unidentified rolling object and define it as "not a truck, not an airplane, not a motorcycle, not a helicopter, not a snickers bar on wheels". The same logic should apply to alien craft. First they were called flying saucers, and then they were popularized under the name UFOs. But either way, we're still talking about the same thing. All the other anomalous phenomena fall under the heading of UAP ( unidentified aerial phenomena ), introduced by NARCAP. These are well established historical facets of ufology, yet as a ufologist, I still see far too much confusion about them ( even denial ) both within and outside the field, and this is what is preventing us from "piercing the veil" we talked about earlier. But when we view the subject as outlined here, we can clearly see that the veil has already been pierced. It's just that the hole is very small. What we need to do now is focus in on that tiny point in order to widen the aperture.
