Yes. People are
immigrating between
countries all the time.
Now as for
extraterrestrial, I'm not so sure.
It seems very likely that there is life somewhere else in the universe (though far from the "with so many planets, it's inconceivable that there isn't" that most people seem to believe. They don't know the first thing about probability) however "intelligent life" I'm not so sure about.
First you have to consider "what is intelligence?" Are dogs intelligent? Are cats? Are Humans? What we consider "intelligent" seems a very narrow spectrum to me. (So does what we consider life, actually, which is what I'm going to start talking about in the next paragraph instead.)
We, for some unknown reason, seems to think that life requires water, probably because all life we know about does. (Duh! All life we about is on Earth. It all evolved in the same environment, and possibly all from the same cell.)
I have absolutely no idea how to conclude this writeup--the beginning and middle weren't that great either--so I'll just say this: ...umm...I can't think of anything to say. Never mind.