Its hard to imagine so many people could have known about this for so long, yet it remained secret. I expect you could keep something like an assassination secret since everyone who knows about it is probably in some way complicit. Wouldn't be the case here.
Also of course the energy required to get to Earth from somewhere else, for an organism that used any kind of "vehicle" we could recognize as such, would be enormous.
Also of course the energy required to get to Earth from somewhere else, for an organism that used any kind of "vehicle" we could recognize as such, would be enormous.
But, good to stay open-minded.