There are so many explanations as to what they are. Anywhere from us from the future to an ancient race making us to mine gold for them. Think about that last one there, we like shiny things if it is not shiny we probably don't like it. Anyway i got to thinking after watching a movie (the fourth kind if the link doesn't work) and wondered what are the public's thoughts.
The reason we crave gold is it is a precious metal. Precious because there is a very limited supply of it, it is not a common metal.
And by their very nature, they are aliens. They exist, the mathematic probability of them existing is huge, so they must exist. Whether they have visited earth is another debate altogether.
