In astronomy, the geocentric model is a superseded description of the Universe with Earth at the center. Under most geocentric models, the Sun, Moon, stars, and planets all orbit Earth. The geocentric model was the predominant description of the cosmos in many European ancient civilizations, such as those of Aristotle in Classical Greece and Ptolemy in Roman Egypt, as well as during the Islamic Golden Age.
Figure of the heavenly bodies — An illustration of a non-Ptolemaic geocentric system by Portuguese cosmographer and cartographer Bartolomeu Velho, 1568 (Bibliothèque Nationale, Paris)
Pages from 1550 Annotazione on Sacrobosco's De sphaera mundi, showing the Ptolemaic system.
This drawing from an Icelandic manuscript dated around 1750 illustrates the geocentric model.
Astronomy is a natural science that studies celestial objects and the phenomena that occur in the cosmos. It uses mathematics, physics, and chemistry in order to explain their origin and their overall evolution. Objects of interest include planets, moons, stars, nebulae, galaxies, meteoroids, asteroids, and comets. Relevant phenomena include supernova explosions, gamma ray bursts, quasars, blazars, pulsars, and cosmic microwave background radiation. More generally, astronomy studies everything that originates beyond Earth's atmosphere. Cosmology is a branch of astronomy that studies the universe as a whole.
The Paranal Observatory of European Southern Observatory shooting a laser guide star to the Galactic Center
Astronomical Observatory, New South Wales, Australia 1873
19th-century Quito Astronomical Observatory is located 12 minutes south of the Equator in Quito, Ecuador.
The Suryaprajnaptisūtra, a 6th-century BC astronomy text of Jains at The Schoyen Collection, London. Above: its manuscript from c. 1500 AD.
