Answer:
observations of the phases of VENUS could not be explained by Ptolemy's epicyclic model
Explanation:
Ptolemy mentioned that the epicycles were based on the Earth-Sun axis for both Venus and Mercury. They had to be between us and Sun, and thus the telescope would always have them appear to be crescents. Galileo discovered that Venus was going through the entire process of motion showing that it fully revolved round the Sun in his heliocentric theory, as foretell by Copernicus.
