Question

Ptolemy, and others, idea that suggests the Earth is at the center of the universe and all other planets orbit it.

Answer 1

The idea that suggests the Earth is at the center of the universe, with all other celestial bodies, including the Sun, Moon, stars, and planets, orbiting it is known as the **geocentric model**. This model was most famously formulated by the ancient Greek astronomer **Ptolemy** in the 2nd century CE. His system, described in the work known as the **Almagest**, provided a complex framework of epicycles (small circular orbits) to explain the apparent retrograde motion of planets.

The geocentric model dominated astronomical thought for many centuries and was widely accepted until it was eventually replaced by the **heliocentric model**, proposed by Nicolaus Copernicus in the 16th century, which posited that the Sun is at the center of the universe and the Earth, along with other planets, orbits around it.