Haven't looked yet, but relax, sure there are aliens out there (duh) but, I don't even think their evil. They obviously have power hella greater than out own, after all, they did discover us before we discovered them, and I'm sure no nukes or anything like that would stop them from invasion. But think about it, how long have they been... around? possibly hundreds, maybe thousands of years, yet, the planets still intact.. what does that tell you?
They'll prolly stay in hiding to save man from himself. I think they're just interested in us, and feel some sort of need to guide us. But, as for dominating the planet... For what purpose? Our tech. is shitty, and we are inferior to them. Their planet's better suited for them.
They wont blow it up either. Again... big explosion.. when the explosion clears... then what? They're too smart for that. Do our scientists blow shit up for the sake of amusement? Hell no.
We knew they were there, and they knew we knew they're there (i know, bad scentence). But come on, they've known about us for many years, and I'd bet it dates back to the tens of thousands of years.
So, don't worry, they aren't savage barbarians, or they would have never developed the technology capable of reaching planets far from their own.
I think they're staying in hiding because they know it will screw with religonal stuff, and they don't want us to... have major conflict over something like that and risk the planet and their research. Like I said.. they might show in the event we destroy the planet... but then again, we let "nature take it's toll" and not interfere when we see things get killed or whatever, maybe they'll do the same... but I dunno, I doubt it.
So, yeah, relax.
Yeah, I'm human...