Stamp of the Day: UFOs

I don't know if there are any aliens out there, but of course there are Unidentifiable Flying Objects, which really can be anything you can't identify, right? But until I have seen an alien, I won't believe in them. But I do believe there are some stamps that depict various UFOs, because these stamps have been seen, right here on this blog. (Lively dinner and lunch discussions here at home lately, with a variety of opinions... :) The stamps are supposed to show different UFOs seen over America, especially in Roswell, New Mexico in 1947. I have no idea why Tanzania would print these stamps, maybe so they could corner a new market in philately? The science fiction-stamp collector cross-over? My favorite design is the bottom middle one.