Indeed, a mothership, or many during those times when visibility would be disbursed. Positioned such that it can hardly be missed by the many now looking for Planet X, and noticed casually by those gazing at the sunrise or sunset. This has a two-fold effect.
But an underlying message also is being relayed, that man is not the unique lifeform he often assumes, alone as an intelligent and technological creature, so they look past the coming disasters to what might be coming next, from the heavens. As this will be invariably received as a warning, the human establishment reaction as a refusal to help, and thus the mothership remembered in this context.