The rich potential of the nineteenth-century friendship and collaboration between the artist Christoffer Wilhelm Eckersberg and the mathematician and astronomer Georg Frederick Ursin has never been explored, and outside of Denmark their important contributions are little known. Eckersberg, considered the father of Danish painting, is one of the great figures of Danish art, together with the sculptor Bertel Thorvaldsen. The artist’s dagbøger or journal, in which he recorded his activities in brief entries – which begins with his Parisian period (1810–1813) in the studio of Jacques-Louis David and his Roman sojourn (1813–1816) – enables us to chart their associations and common astronomical interests more fully than is usually the case during the epoch. Among their collaborations are two books on perspective An Attempt at a Guide to the Use of Perspective for Young Painters and Linear Perspectives Applied to Painting: A Series of Perspective Studies, which grapple with expanding Albertian perspective for current artistic practice. An exploration of the two individuals’ intriguing intersections, including their shared passion for solar eclipses, offers insights into a number of enigmatic works by Eckersberg, as well as the turbulent cultural and political time of nationalism in which they lived. The article also presents for the first time a chronological study of Eckerberg’s historical works on the theme of King Christian IV visiting Tycho Brahe in his world-class observatory on the island of Hven and the role Ursin played in the fascinating sequence of drawings, paintings, and prints. Finally, the study solves the iconographic mystery surrounding two works that have remained a puzzle in Danish art since Eckersberg created them.