Solar system and comets. 18th-century diagrams of the solar system and the orbits of the known planets, with the orbits of five comets. These are dated to 1337, 1590, 1661 (return predicted in 1789), 1680, and 1682 (Halley's Comet, return predicted in 1758). Across bottom are diagrams of three different projections used in astronomy: an oblique sphere (the night sky seen from anywhere except the poles or equator), a right sphere (the night sky seen from the equator), and a parallel sphere (the night sky seen from the poles). This page is from 'A complete system of geography' (London, 1747, 2 volumes) by Emanuel Bowen (c.1694-1767).