The Earth is slowly losing it's influence on the orbit of the moon. Eventually, the moon will be sort of 'sling-shotted' into the deep reaches of space.  Assuming that this is fact, what if, theoretically, when the moon blasts off into space after Earth loses gravitational influence on it, what if the trajectory is heading straight towards a theoretical intelligent alien race? What if they saw the flag(s) that wave on it's surface? What would their questions be as something that looks to be a giant moon-sized weapon is hurdling at their planet, as they are waiting for their doom?  Idk, but it's fun to think about.
the flags are probably not in any waveable condition anymore