I always find myself thinking about this stuff a lot. I just can't begin to understand how something like space exists and can be so big. It pretty much never ends and if we can't even fly to certain planets then no one will ever see what else is out there.
There has to be other life, and be it aliens or not something else is out there. Even the term alien is weird to me, but there is definitely more life out there besides our own.
However I don't think we've ever had "alien encounters". If we can't go see them over on their planets how can they come see us? They have all this advanced technology and built it all somehow? Come teach us..