A fleet of fuel depleted star ships enters earth orbit and descends inexorably towards the Antipodes.
A lone sheriff stands astride the Sydney Harbour Bridge shouting " stop the boats! We stopped the boats oooo errrr!"
Seriously , apart from thermophilic bacteria or extreme cold pressure vacuum loving bugs, in my mind Hawking hit the nail on the tyre by using the example of Captain Cook vs the South Pacific islanders. Faced with a vastly superior technological race ( assumption holds if you cruise between stars), they got beads, influenza, syphilis and exploitation, Cook ( before he was murdered) to be far was apparently a decent man, as was Banks?, but they opened up half the world to speculators, venereal priests and psychotic mostly pommie governors.
Not a good start.
If they cruise from Rigel to here, they are not on a peace mission my friends.
The mote in gods eye/ foot fall/ the forge of god- all good fiction to whet your drake addled brain pans.
All we can do is throw faeces!!!!! (Again)
