Seleucus of Seleucia was an ancient astronomer who defended heliocentrism, arguing that Earth orbits the Sun and rotates on ...

Dallas shows an orrery – a mechanical model of the solar system. Before the 17th century most people believed in a geocentric model of the solar system. Dallas explains the geocentric model and ...

Greek astronomer Claudius Ptolemy, who lived in Egypt, built upon Babylonian knowledge in his geocentric model of the universe. This model, which placed the Earth at the center of the universe ...

The planets were thought to go around the Earth, in perfectly circular orbits. This so-called Geocentric model was the construction of famous Greek mathematician, astronomer Ptolemy. The model ...