The Sphere of the World

...and into the seven spheres of the seven planets. Some of these are larger and others smaller, depending on how much they approach or recede from the firmament In the geocentric model, the "firmament" is the outermost sphere of the fixed stars; the closer a sphere is to this outer limit, the larger its circumference.. Hence, among them, the sphere of Saturn is the largest, whereas the sphere of the Moon is the smallest, just as is shown in the following illustration.

A woodcut geocentric astronomical diagram (schema mundi) consisting of eleven concentric circles. The central core represents the Earth, divided into four quadrants (likely representing the four known elements: Earth, Air, Fire, and Water), surrounded by a ring of wavy lines signifying the element of water. Proceeding outward, the spheres are labeled with planetary symbols: the Moon (☾), Mercury (☿), Venus (♀), the Sun (☉), Mars (♂), Jupiter (♃), and Saturn (♄). The outermost ring represents the Zodiac (Firmamentum), divided into twelve numbered segments, each containing a zodiacal symbol: Aries (♈︎), Taurus (♉︎), Gemini (♊︎), Cancer (♋︎), Leo (♌︎), Virgo (♍︎), Libra (♎︎), Scorpio (♏︎), Sagittarius (♐︎), Capricorn (♑︎), Aquarius (♒︎), and Pisces (♓︎). Small asterisks representing the fixed stars are distributed within the outer planetary spheres.

Symbols of the signs of the zodiac

Symbols of the planets