[ben_w]

Hiding would be good if you could do it, but:

(a) to the best of everyone’s knowledge it is impossible to hide your heat signature in space, let alone hide the shadow of a planet blocking the light of its star (metamaterial cloaks are far too frequency-specific)

(b) the biosignatures we’re looking for right now are anything out of chemical equilibrium, so a planet-dwelling civilisation would only hide from us if they wiped out their surface and ocean ecosystems at the very least