Maybe it’s one of those generational interstellar starships manned by the great, great, great great, great, great grandchildren of the original brave crew that set out from a dying planet on the hope of continuing their species beyond the stars.
Or maybe it’s just a big rock...
I dunno
Maybe it’s one of those generational interstellar starships ... Or maybe it’s just a big rock..
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Or maybe its an indirect attack by an alien species in hiding - cf the Dark Forest theory