Sun and earth. In his translation of Ursin's Populært Foredrag over Astronomien Jónas writes: "The earth is a dark body and the sun illuminates only one half of it at a time, dividing it between light and darkness. As a result there is a shadow boundary [forsæluhringur] around the whole earth where light and darkness meet." (3E447)

Source: Populært Foredrag over Astronomien, Table III, Figure 36 [digitally edited].