Some UFO's ARE from another planet.

Your first point: I've already spoken about the size of the Universe - and I think you're being a tad optimistic. Further debate can't settle this disagreement; instead, I urge you to go away and learn about the spaces and sizes and numbers involved, and compare that to the complexity of the life we're talking about. It's a much, much longer shot than you're making it sound. Not that I'm saying life won't evolve anywhere else in the Universe - on the contrary, it's not all that unlikely. But the kind of life we're talking about has got to do more than just evolve; it has to reach a level of complexity unimaginable to us, and don't underestimate the problems such a civilisation will have to overcome along the way - global resource and climate regulation is a hellishly complicated affair - I'm not even sure it's doable. And then, minimising the whole process to enable a spaceship to travel to a new solar system, in the face of all the laws of entropy. Scifi makes this stuff look easy. The sheer wrongness of this impression is comparable to the interstellar distances we're talking about: it may be that such a task is simply physically unattainable. It may be that several of these freakish cultures of bacteria spontaneously evolved out there, and that none of them made it off their planet before the meteorite struck, or away from their sun before it went nova. I'm not even going to start on faster-than-light travel. I damn well hope it's possible, but I'm not holding my breath. But why any civilisation advanced enough to use it would still be using spaceships, or indeed any physical equipment at all that was big enough to be a UFO, I can't imagine. So the general point of the above four paragraphs was that the odds of your average UFO being an alien are not big. Impossible to quantify, perhaps, but certainly not big. Small enough to make the tenuous localised-freak-weather-phenomenon alternatives a much more likely (though unsatisfying) explanation. So what of the evidence to the contrary? Well, it seems to me that when something happens that's completely outside our daily experiences - take any given reporting - there's a definite double standard when it comes to explanations. Unfortunately, to an unlucky majority, science is boring. Scientific explanations tend to make everything mundane again - while reminding us how stupid we are because we didn't really understand them. Here's a fantastic occurrence, like nothing we've seen before, and science will explain it. And that will make it dull again, because we didn't really want it explained. We wanted something genuinely significant to have happened. So, a scientist must obey strict principles when coming up with his explanation. Once he has, he must then face down a barrage of criticisms from people who do not want to hear it. And often, given that he was forced to build his theory on unrepeatable, anecdotal and often very dubious data, his theory will indeed come crashing down. And so the ufologists congratulate themselves. Because after all, noone wants to nitpick their explanation. And noone can: anything that doesn't add up is simply scary advanced alien technology. It may as well be the Holy Spirit, because it can be as mysterious and all powerful as needed. Given that situation, you'll forgive me for ignoring your own alternative explanations. They're awesome, every one, especially the space raptors. I'm also going to have to be a skeptic and discount the evidence you provided - unless you can provide sources. Anecdotes and rumours do not a good study make. The difficulty here is that objective reality is composed of things happening, while the human mind is programmed to think in stories. Aliens and space raptors are stories. Regrettably, until the quantum physicists tell me otherwise, I have to assume that reality takes precedence over stories.