Tychonic solar system. 18th-century illustration of the 1570s geo-heliocentric solar system (centre) of Danish astronomer Tycho Brahe (upper left), circled by the signs of the zodiac. A modification to this system (lower left) was proposed by Italian Jesuit astronomer Giovanni Battista Riccioli (upper right), with an Egyptian modification at lower right. The Tychonic system has the Sun, Moon and stars orbiting the Earth, and the planets orbiting the Sun. The upper corners show the difference in the relative sizes of the planets in the two systems. This depiction by German geographer and cartographer Johann Baptist Homann dates from 1716.