If extra-terrestrial intelligent life visited the solar system the first things we would notice would be:
A) Tourists
B) Alien equivalent of David Attenborough
C) Worse, Alien equivalent of Darwin stealing random people in a rather obvious fashion and setting up on some random island
D) Total and utter annihilation of the species to harvest the resources of earth/stop us from ever becoming any form of threat.
E) Off world slavery.
F) Colonization.
I do not buy the "Aliens will have our best interests at heart" I mean, did WE ever have the best interests of anyone at heart when we colonized them? No, We went in, shot people, give the survivors diseases and took everything of worth at best, enslaved millions of people to grow shit that we wanted to sell whilst doing all of the above at worst.
Nor do I buy the "Aliens who have the power to travel the cosmos would then proceed to abduct random impressionable farmers/crash into earth for no given reason". Finally, There is no benefit from a ship the size of a planet nor parking said ship near a star (Stars are hot. Very, very hot) so I am inclined to go for what the scientists say over some dude on youtube who, chances are, wears a tinfoil hat.
I mean, Why create a ship the size of a planet? Sure, it can apparently be cloaked but... Space has debris, debris is dangerous. Ship the size of a planet would attract a lot of debris. Ship the size of a planet is a big target so is useless if someone wanted to blow it up. Ship the size of a planet is not covert so useless for studying anything.
Ship the size of a planet would cost so goddam much to build as to be pointless. I mean, look at the Death Star!
