The geocentric model of the universe is an ancient astronomical theory that places Earth at the center of the universe, with all celestial bodies—including the Sun, Moon, planets, and stars—orbiting around it. This model was widely accepted in many ancient civilizations, including those of Greece, Egypt, and China.
Key Features:
- Earth-Centered – The Earth is fixed and does not move.
- Spherical Heavens – Celestial objects move in circular orbits around Earth.
- Epicycles and Deferents – To explain the observed retrograde motion of planets, Greek astronomers like Ptolemy introduced small circular orbits (epicycles) on larger circular paths (deferents).
Historical Background:
- Aristotle (4th century BCE) – Supported the geocentric model based on philosophical and observational arguments.
- Ptolemy (2nd century CE) – Refined the model in his work Almagest, making it mathematically complex but more accurate in predicting planetary movements.
Decline of the Model:
The heliocentric model, proposed by Copernicus (1543) and later supported by Galileo, Kepler, and Newton, demonstrated that the Sun, not Earth, is at the center of the solar system. This led to the geocentric model being replaced in modern astronomy.