Humans are always imagining what it would be like if aliens visited earth? Are we ready? Countless books and sci-fi movies speculated how it would be.
Astronomers have a series of recommended actions to be taken after detecting signal from far away civilization, but it seems that we don't have any plan if E.T's land here on earth. Or maybe it's not for public.
If our new visitors turn up to be hostile it would mean end of the world. Any extraterrestrial civilization capable of journeying from its own star system to Earth would be far more technologically advanced than humanity is. It would be like going into war against Roman legion with U.S Air Force.
The arrival of alien spaceships on Earth would present a much more immediate potential threat than a signal detection. So how would humanity react to a possible invasion? We may just have to wait and see.