[Flyndaran]

That would render any form of astronomy not-planet based impossible.

Or create a separate system of arrays dedicated to detecting probe signals sent by worlds they replace.
Okay, we're getting weak radio from Voyager 14 half way to Alpha Centauri and Curiosity 5 telling us that the habitat is nearing completion.
BLIP!
Wait, is that half a message from Mars demanding their Danegeld or they'll fire their disintegrator ray? What does "blocking Venus" even mean?
BLIP!