Editing Anaximander (section)

=== Cosmology ===

[[File:Anaximander cosmology-en.svg|thumb|left|280px|Map of Anaximander's universe]]

Anaximander's bold use of non-[[Greek mythology|mythological]] explanatory hypotheses considerably distinguishes him from previous cosmology writers such as [[Hesiod]].{{sfn|Rovelli|2023|pp=42–43}} It indicates a pre-Socratic effort to demystify physical processes. His major contribution to history was writing the oldest prose document about the Universe and the origins of life; for this he is often called the "Father of [[Cosmology]]" and founder of astronomy. However, [[pseudo-Plutarch]] states that he still viewed celestial bodies as deities.<ref>Pseudo-Plutarch, ''Doctrines of the Philosophers'', i. 7</ref> He placed the celestial bodies in the wrong order. He thought that the stars were nearest to the Earth, then the Moon, and the Sun farthest away. His scheme is compatible with the [[Indo-Iranians|Indo-Iranian]] philosophical traditions contained in the Iranian [[Avesta]] and the Indian [[Upanishads]].<ref>{{cite journal |last1=Marcovich |first1=Miroslav |date=June 1975 |title=Reviewed Work: Early Greek Philosophy and the Orient by M. L. West |journal=Gnomon |volume=47 |issue=4 |pages=321–328}}</ref>

[[File:Persectives of Anaximander's universe.png|thumb|right|350px|Illustration of Anaximander's models of the universe. On the left, daytime in summer; on the right, nighttime in winter. Note the sphere represents the combined rings of all of the stars about the very small inner cylinder which represents the Earth.]]

At the origin, after the separation of hot and cold, a ball of flame appeared that surrounded Earth like bark on a tree. This ball broke apart to form the rest of the Universe. It resembled a system of hollow concentric wheels, filled with fire, with the rims pierced by holes like those of a flute. Consequently, the Sun was the fire that one could see through a hole the same size as the Earth on the farthest wheel, and an eclipse corresponded with the [[Occultation|occlusion]] of that hole. The diameter of the solar wheel was twenty-seven times that of the Earth (or twenty-eight, depending on the sources)<ref>In ''Refutation'', it is reported that the circle of the Sun is twenty-seven times bigger than the Moon.</ref> and the lunar wheel, whose fire was less intense, eighteen (or nineteen) times. Its hole could change shape, thus explaining [[lunar phase]]s. The stars and the planets, located closer,<ref>Aetius, ''De Fide'' (II, 15, 6)</ref> followed the same model.<ref>Most of Anaximander's model of the Universe comes from pseudo-Plutarch (II, 20–28):

: "[The Sun] is a circle twenty-eight times as big as the Earth, with the outline similar to that of a fire-filled chariot wheel, on which appears a mouth in certain places and through which it exposes its fire, as through the hole on a flute. [...] the Sun is equal to the Earth, but the circle on which it breathes and on which it's borne is twenty-seven times as big as the whole earth. [...] [The eclipse] is when the mouth from which comes the fire heat is closed. [...] [The Moon] is a circle nineteen times as big as the whole earth, all filled with fire, like that of the Sun".</ref>

Anaximander was the first astronomer to consider the Sun as a huge mass, and consequently, to realize how far from Earth it might be, and the first to present a system where the celestial bodies turned at different distances. Furthermore, according to Diogenes Laertius (II, 2), he built a [[celestial spheres|celestial sphere]].{{failed verification|date=October 2023}} This invention undoubtedly made him the first to realize the [[Axial tilt|obliquity]] of the [[Zodiac]] as the Roman philosopher [[Pliny the Elder]] reports in ''[[Natural History (Pliny)|Natural History]]'' (II, 8). It is a little early to use the term [[ecliptic]], but his knowledge and work on astronomy confirm that he must have observed the inclination of the celestial sphere in relation to the plane of the Earth to explain the seasons. The [[doxography|doxographer]] and theologian Aetius attributes to Pythagoras the exact measurement of the obliquity.