Nothing quite like the modern science of astrophysics existed at the time Giovanni Riccioli made his observations of Venus in the first half of the seventeenth century. Even after the introduction of the telescope in the same era, the study of astronomy was largely one of phenomena only loosely attached to concepts of physics yet still firmly associated with the pseudoscience of astrology. Astronomers of the late pre-telescopic era such as Tycho Brahe (1546–1601) made precise observations of the positions of the planets that were used as inputs to mathematical models of their positions, but the models largely existed only to validate the preexisting belief in an Earth-centered Solar System. As it turns out, the seeds of geocentrism’s undoing were already sown in Brahe’s measurements. It just took an old idea to make them grow and bloom.