Jupiter. Michael Scot, Liber de signis et ymaginibus celi. Wellcome Library MS 509 (ca.1450-60, North Italy), f.23v
Jupiter completes its circuit in twenty years. Its sphere is 20,192,626 miles thick and the planet itself has a diameter of 29,641 miles. It is clear and pure and tempers the evil influence of Saturn. It causes ‘good and useful effects’ on the elements below. Jupiter is bright and its colour is white.