Let's say they want to try and decide between the heliocentric (Sun-centered) model, and a model in which everything revolves around Mercury. Someone suggests looking at Earth, to see how lit-up it can look, like Galileo did with Venus. Let's assume you have a telescope that can magnify Earth well enough to see any phases it might have. Would this work well, for trying to tell the difference between the heliocentric and Mercury-centric models